The commandment of purification from tsaraat that it be with certain species: That purification from tsaraat — whether tsaraat of a person, a garment or a house — be with cedar wood, hyssop, wool dyed red, two birds and living water, and that he do with them everything that is written about the matter, as it is stated (Leviticus 14:2), “This is the law of the metsora, etc.” to the end of the section. And three types of purifications are mentioned in the Torah, and these are them: Water, and this type, by water, includes the purification of every impurity — meaning to say it is impossible for any impure thing to emerge from impurity without water; and the second type is sprinkling water, and that is the type that is specific for the impurity of a dead body; and the third type, the cedar wood, hyssop, wool dyed red, two birds and living water, and it is the type that is specific for tsaraat. The Sages informed us of a bit of a hint in the matters of the purification of the metsora with these things. As they, may their memory be blessed, said (Pesikta DeRav Kahanah 14) that the matter is to fix in the soul of the metsora that if, before the illness came to him, he was haughty-hearted like the cedar — by way of metaphor, since it is a tall tree — he should lower himself like the hyssop. It is said about the reason of the birds (Arakhin 16b) [that] he did an act of chattering — meaning to say, he spoke many words of evil speech — therefore, he must sacrifice birds that constantly chirp. And with the wool dyed red (shani tolaat), I do not know or remember anything that they, may their memory be blessed, said about it. And it is possible that it is also a hint that he should lower himself; and it would be a hint from its name [as it is called,] worm (tolaat).
And about the reason that water purifies everything impure, I would think on the side of the simple understanding that it is in order that a man see himself with the immersion as if he is created at that time, [just] like the whole world was water before man was upon it — as it is written (Genesis 1:2), “and the spirit of God floated upon the face of the waters.” And through this comparison, he shall place upon his heart that [just] like he is renewed in his body, he [must] also renew his actions for the good, fix his actions and be exacting in the way of God, blessed be He. And therefore the Sages said that the purification is not fit with water that is in a vessel, but rather only with living water — or collected [water], which is on the ground and, in any case, not in a vessel — in order to place in his heart the thought as if the world was entirely water, and [that] he is renewed with his emerging from them, as we said. But if the water was in a vessel — or even if it passed through a vessel — this matter that we said would not be set in the thought of the one immersing. As there is a limit to all that is in a vessel, which is the creation of the hands of man. And therefore when he immerses in a vessel, he will not think as if the whole world is water like at the beginning [of Creation], and that he is renewed at that time. ‘And the one who accepts, will accept; and the one who refrains will refrain.’
From the laws of the commandment is that which they, may their memory be blessed, said (Mishnah Negaim 14:1), “How does one purify the metsora? He would bring a new earthenware pitcher and place within it a reviit of living water,” with which it would be fitting to consecrate the sprinkling water — and that measure is [rabbinic] (Sotah 16b) — “and he would bring two wild birds” that are pure, for the sake of the purification of the metsora; as it is stated (Leviticus 14:4), “and it shall be taken for the one being purified.” He slaughters the clarified (meaning, choice) of the two of them upon the water in the earthenware vessel and squeezes until the blood is recognizable in the water. And he digs and buries the slaughtered bird before him — and this is a tradition from what was heard. He takes cedar wood — and its commandment is that it be an ell long and its width be like a quarter of a foot of the feet of a bed; and not less than a handbreadth of hyssop that does not have an adjunct name; wool dyed red, the weight of which is a shekel, and if he mixed [its color], he disqualified it, like the dying of the aquamarine, which is disqualified by mixing. And all the measures are a law [from Moshe at Sinai] (Eruvin 4a). And he takes the living bird with the three of them; and the four species impede one another (Menachot 27a); and cedar wood or hyssop that have been peeled are disqualified. He ties the hyssop to the cedar wood with a strip of crimson fabric and surrounds them with the tips of the wings and the tip of the tail of the living bird. And he dips the four of them in water that is in the vessel and in the blood that is [in] it; “and sprinkles seven times on the back of the hand of the metsora.” And he sends away the bird. And how does he send it away? If he is standing in the city, he throws it out of the wall (Kiddushin 57b). “He does not face the sea nor the city, but the desert, as it is stated (Leviticus 14:53), ‘to outside the city towards the field’” (Mishnah Negaim 14:2). [If] he sent it and it comes back, he again sends it away — even a hundred times.
And afterwards, the priest shaves the metsora. And how does he shave him? He passes the razor over his visible flesh — and even [on] the underarm and the pubic area and all the rest of the body — until he becomes [smooth] like a gourd, as it is stated (Leviticus 14:9), “all of his hair.” If so, why does it state, “his head, his beard, and his eyebrows?” To include everything that is like them and to exclude hair that is in the nose, since it is not seen. And afterwards he washes his clothes and immerses, and is purified with this from passing on impurity from his resting and sitting [upon something]; and he can come inside the [city] wall. And he counts seven days; and during those seven days, he is prohibited in sexual relations, as it is stated, “outside of his tent” — teaching he is forbidden in sexual relations. But a metsora’at is permitted in sexual relations. All of these seven days, he is still a source of impurity and renders a person and vessels impure with touch, but he does render impure with carrying — as behold it states (Leviticus 14:9), “And it shall be on the seventh day, etc. and he shall wash his clothes” — teaching that he was rendering clothes impure. And [just] like he was rendering clothes impure, so [too] was he rendering a man impure with touch — since all that renders a person impure, renders clothes impure; and all that does not render a person impure, does not render clothes impure (Mishnah Kelim 1:1). And on the seventh day, the priest shaves him a second [time] like the first shaving. And [the metsora] washes his clothes and immerses and is purified from rendering others impure. And behold he is like all who have immersed during the day, and can eat from the tithe; when his sun sets, he can eat from the priestly tithe; [and] when he brings his atonement, he can eat from consecrated foods. The slaughter of the bird, the shaving and the sprinkling are during the day, but all the other procedures are whether during the day or during the night. These [three things] are with men, but all the rest are even with women. These are with priests, but all the rest are even through an Israelite. And it is a commandment for the same priest who rendered him impure [to render him pure, as it is stated (Leviticus 13:59)], “to render him pure or to render him impure.” And the rest of its details are in Tractate Negaim.
And this purification is practiced in every place and at all times that there is a priest that is wise about ailments. So did Rambam, may his memory be blessed, explain (and so did I see in Sifra). And one who transgresses it and did not do it like its statute, has violated a positive commandment.
מִצְוַת הַטַּהֲרָה מִן הַצָּרַעַת שֶׁתִּהְיֶה בְּמִינִים יְדוּעִים – לִהְיוֹת הַטַּהֲרָה מִן הַצָּרַעַת בֵּין צָרַעַת אָדָם אוֹ בֶּגֶד אוֹ בַּיִת, בְּעֵץ אֶרֶז וְאֵזוֹב וּשְׁנִי תּוֹלַעַת וּשְׁתֵּי צִפֳּרִים וּמַיִם חַיִּים, וְשֶׁיֵּעָשֶׂה בָּהֶן כָּל מָה שֶׁכָּתוּב בָּעִנְיָן שֶׁנֶּאֱמַר (ויקרא יב ב) זֹאת תִּהְיֶה תּוֹרַת הַמְּצֹרָע וְגוֹ' כָּל הַפָּרָשָׁה. וּשְׁלֹשֶׁת מִינִין שֶׁל טָהֳרָה הֻזְכְּרוּ בַּתּוֹרָה. וְאֵלּוּ הֵן מַיִם, וְזֶה הַמִּין שֶׁל מַיִם יִכְלֹל טַהֲרַת כָּל טָמֵא, כְּלוֹמַר שֶׁאִי אֶפְשָׁר לְכָל טָמֵא לַעֲלוֹת מִטֻּמְאָה כִּי אִם בַּמַּיִם. וְהַמִּין הַשֵּׁנִי מֵי נִדָּה, וְהוּא הַמִּין שֶׁל הַטַּהֲרָה הַמְיֻחָד בְּטֻמְאַת מֵת. וְהַמִּין הַשְּׁלִישִׁי, עֵץ אֶרֶז וְאֵזוֹב וּשְׁנִי תּוֹלַעַת וּשְׁתֵּי צִפֳּרִים וּמַיִם חַיִּים. וְזֶה הַמִּין מְיֻחָד לַצָּרַעַת. קְצָת רֶמֶז בְּעִנְיְנֵי טָהֳרָתוֹ שֶׁל מְצֹרָע בִּדְבָרִים אֵלּוּ הוֹדִיעוּנוּ חֲכָמִים עַל צַד הַפְּשָׁט. שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (פסיקתא דרב כהנא יד) שֶׁהָעִנְיָן הוּא לִקְבֹּעַ בְּנַפְשׁוֹ שֶׁל מְצֹרָע, שֶׁאִם הָיָה טֶרֶם בָּא עָלָיו הַחֹלִי גְּבַהּ לֵב כְּמוֹ הָאֶרֶז עַל דֶּרֶךְ מָשָׁל שֶׁהוּא אִילָן גָּבוֹהַּ, יַשְׁפִּיל עַצְמוֹ כְּאֵזוֹב, וְאָמְרוּ בְּטַעַם צִפֳּרִים (ערכין טז ב) הוּא עָשָׂה מַעֲשֵׂה פָּטִיט, כְּלוֹמַר שֶׁהִרְבָּה דְּבָרִים בְּלָשׁוֹן הָרַע, לְפִיכָךְ יַקְרִיב צִפֳּרִים שֶׁהֵם מְצַפְצְפִים תָּמִיד. וּבִשְׁנִי הַתּוֹלַעַת אֵינִי יוֹדֵעַ וְנִזְכָּר שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה עָלָיו דָּבָר. וְאֶפְשָׁר גַּם כֵּן שֶׁהוּא רֶמֶז שֶׁיַּשְׁפִּיל עַצְמוֹ וְיִהְיֶה הָרֶמֶז מִצַּד הַשֵּׁם שֶׁל תּוֹלַעַת.
The commandment of purification from tsaraat that it be with certain species: That purification from tsaraat — whether tsaraat of a person, a garment or a house — be with cedar wood, hyssop, wool dyed red, two birds and living water, and that he do with them everything that is written about the matter, as it is stated (Leviticus 14:2), “This is the law of the metsora, etc.” to the end of the section. And three types of purifications are mentioned in the Torah, and these are them: Water, and this type, by water, includes the purification of every impurity — meaning to say it is impossible for any impure thing to emerge from impurity without water; and the second type is sprinkling water, and that is the type that is specific for the impurity of a dead body; and the third type, the cedar wood, hyssop, wool dyed red, two birds and living water, and it is the type that is specific for tsaraat. The Sages informed us of a bit of a hint in the matters of the purification of the metsora with these things. As they, may their memory be blessed, said (Pesikta DeRav Kahanah 14) that the matter is to fix in the soul of the metsora that if, before the illness came to him, he was haughty-hearted like the cedar — by way of metaphor, since it is a tall tree — he should lower himself like the hyssop. It is said about the reason of the birds (Arakhin 16b) [that] he did an act of chattering — meaning to say, he spoke many words of evil speech — therefore, he must sacrifice birds that constantly chirp. And with the wool dyed red (shani tolaat), I do not know or remember anything that they, may their memory be blessed, said about it. And it is possible that it is also a hint that he should lower himself; and it would be a hint from its name [as it is called,] worm (tolaat).
וּבְטַעַם הַמַּיִם שֶׁיְּטַהֲרוּ כָּל טָמֵא אֶחְשֹׁב עַל צַד הַפְּשָׁט כִּי הָעִנְיָן הוּא כְּדֵי שֶׁיִּרְאֶה הָאָדָם אֶת עַצְמוֹ אַחַר הַטְּבִילָה כְּאִלּוּ נִבְרָא בְּאוֹתָהּ שָׁעָה, כְּמוֹ שֶׁהָיָה הָעוֹלָם כֻּלּוֹ מַיִם טֶרֶם הֱיוֹת בּוֹ אָדָם, וּכְמוֹ שֶׁכָּתוּב (בראשית א ב) וְרוּחַ אֱלֹהִים מְרַחֶפֶת עַל פְּנֵי הַמָּיִם. וְיִתֵּן אֶל לִבּוֹ בַּדִּמְיוֹן כִּי כְּמוֹ שֶׁנִּתְחַדֵּשׁ בְּגוּפוֹ יְחַדֵּשׁ גַּם כֵּן פְּעֻלּוֹתָיו לְטוֹב, וְיַכְשִׁיר מַעֲשָׂיו וִידַקְדֵּק בְּדַרְכֵי הַשֵּׁם בָּרוּךְ הוּא. וְעַל כֵּן אָמְרוּ חֲכָמִים שֶׁלֹּא תִּכְשַׁר הַטָּהֳרָה בַּמַּיִם שֶׁבִּכְלִי רַק בְּמַיִם חַיִּים אוֹ מְכֻנָּסִין שֶׁהֵן עַל קַרְקַע וְלֹא בִּכְלִי. מִכָּל מָקוֹם כְּדֵי לָתֵת אֶל לִבּוֹ בְּמַחְשָׁבָה כְּאִלּוּ הָעוֹלָם כֻּלּוֹ מַיִם, וְהוּא נִתְחַדֵּשׁ בַּעֲלוֹתוֹ מֵהֶן, כְּמוֹ שֶׁאָמַרְנוּ. וְאִם יִהְיוּ הַמַּיִם בִּכְלִי אוֹ אֲפִלּוּ עָבְרוּ עַל כְּלִי, לֹא יִתָּכֵן הָעִנְיָן הַזֶּה שֶׁאָמַרְנוּ אֶל מַחְשֶׁבֶת הַטּוֹבֵל. כִּי יֵשׁ גְּבוּל אֶל כָּל אֲשֶׁר הוּא בִּכְלִי שֶׁהוּא מַעֲשֵׂה יְדֵי אָדָם, וְעַל כֵּן לֹא יַחְשֹׁב בְּטָבְלוֹ בַּכְּלִי כְּאִלּוּ כָּל הָעוֹלָם מַיִם כַּאֲשֶׁר בַּתְּחִלָּה, וְשֶׁהוּא נִתְחַדֵּשׁ לִשְׁעָתוֹ. וְהַשּׁוֹמֵעַ יִשְׁמַע וְהֶחָדֵל יֶחְדַּל (יחזקאל ג כז).
And about the reason that water purifies everything impure, I would think on the side of the simple understanding that it is in order that a man see himself with the immersion as if he is created at that time, [just] like the whole world was water before man was upon it — as it is written (Genesis 1:2), “and the spirit of God floated upon the face of the waters.” And through this comparison, he shall place upon his heart that [just] like he is renewed in his body, he [must] also renew his actions for the good, fix his actions and be exacting in the way of God, blessed be He. And therefore the Sages said that the purification is not fit with water that is in a vessel, but rather only with living water — or collected [water], which is on the ground and, in any case, not in a vessel — in order to place in his heart the thought as if the world was entirely water, and [that] he is renewed with his emerging from them, as we said. But if the water was in a vessel — or even if it passed through a vessel — this matter that we said would not be set in the thought of the one immersing. As there is a limit to all that is in a vessel, which is the creation of the hands of man. And therefore when he immerses in a vessel, he will not think as if the whole world is water like at the beginning [of Creation], and that he is renewed at that time. ‘And the one who accepts, will accept; and the one who refrains will refrain.’
מִדִּינֵי הַמִּצְוָה. מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (נגעים יד א) כֵּיצַד מְטַהֲרִין אֶת הַמְּצֹרָע? מֵבִיא מִזְרָק שֶׁל חֶרֶשׂ שֶׁהוּא חָדָשׁ וְנוֹתֵן לְתוֹכוֹ רְבִיעִית מַיִם חַיִּים הָרְאוּיִין לְקַדֵּשׁ אוֹתָם לְמֵי חַטָּאת. וְשִׁעוּר זֶה (סוטה טז ב) מִדִּבְרֵי סוֹפְרִים. וּמֵבִיא שְׁתֵּי צִפֳּרִים חַיּוֹת טְהֹרוֹת לְשֵׁם טָהֳרַת הַמְּצֹרָע, שֶׁנֶּאֱמַר (ויקרא יד ד) וְלָקַח לַמִּטַּהֵר. וְשׁוֹחֵט אֶת הַבְּרוּרָה (פי, מובחרת) שֶׁבִּשְׁתֵּיהֶן עַל הַמַּיִם שֶׁבִּכְלִי חֶרֶשׂ וּמְמַצֶּה עַד שֶׁיִּהְיֶה הַדָּם נִכָּר בַּמַּיִם, וְחוֹפֵר וְקוֹבֵר הַצִּפּוֹר הַשְּׁחוּטָה בְּפָנָיו, וְדָבָר זֶה קַבָּלָה מִפִּי הַשְּׁמוּעָה. וְנוֹטֵל עֵץ אֶרֶז, וּמִצְוָתוֹ שֶׁיְּהֵא אָרְכּוֹ אַמָּה וְעָבְיוֹ כִּרְבִיעַ כֶּרַע מִכַּרְעֵי הַמִּטָּה. וְאֵזוֹב שֶׁאֵין לוֹ שֵׁם לְוַי לֹא יְהֵא פָּחוֹת מִטֶּפַח. וּשְׁנִי תּוֹלַעַת מִשְׁקָלוֹ שֶׁקֶל, וְאִם טְעָמוֹ פְּסָלוֹ כִּצְבִיעַת הַתְּכֵלֶת שֶׁנִּפְסַל בִּטְעִימָה. וְכָל הַשִּׁעוּרִין (עירובין ד א) הֲלָכָה. וְלוֹקֵחַ עִם שְׁלָשְׁתָּן הַצִּפּוֹר הַחַיָּה. וְאַרְבַּעַת מִינִין אֵלֶּה מְעַכְּבִין זֶה אֶת זֶה (מנחות כז א). וְעֵץ אֶרֶז וְאֵזוֹב שֶׁנִּתְקַלְּפוּ פְּסוּלִין, וְכוֹרֵךְ הָאֵזוֹב עִם הָאֶרֶז בְּלָשׁוֹן שֶׁל זְהוֹרִית, וּמַקִּיף לָהֶם רָאשֵׁי אֲגַפַּיִם וְרֹאשׁ הַזָּנָב שֶׁל [הַ]צִּפּוֹר הַחַיָּה, וְטוֹבֵל אַרְבַּעְתָּן בַּמַּיִם שֶׁבַּכְּלִי וּבַדָּם שֶׁעֲלֵיהֶן, וּמַזֶּה שֶׁבַע פְּעָמִים עַל גַּב יָדוֹ שֶׁל מְצֹרָע וּמְשַׁלֵּחַ הַצִּפּוֹר. וְכֵיצַד מְשַׁלְּחָהּ? (קידושין נז ב) עוֹמֵד בָּעִיר וְזוֹרְקָהּ חוּץ לַחוֹמָה וְאֵינוֹ הוֹפֵךְ פָּנָיו לָאֹהָלִים וְלֹא לָעִיר אֶלָּא לַמִּדְבָּר, שֶׁנֶּאֱמַר (שם יד נג) אֶל מִחוּץ לָעִיר אֶל פְּנֵי הַשָּׂדֶה. שִׁלְּחָהּ וְחָזְרָה חוֹזֵר וּמְשַׁלְּחָהּ, אֲפִלּוּ מֵאָה פְּעָמִים.
From the laws of the commandment is that which they, may their memory be blessed, said (Mishnah Negaim 14:1), “How does one purify the metsora? He would bring a new earthenware pitcher and place within it a reviit of living water,” with which it would be fitting to consecrate the sprinkling water — and that measure is [rabbinic] (Sotah 16b) — “and he would bring two wild birds” that are pure, for the sake of the purification of the metsora; as it is stated (Leviticus 14:4), “and it shall be taken for the one being purified.” He slaughters the clarified (meaning, choice) of the two of them upon the water in the earthenware vessel and squeezes until the blood is recognizable in the water. And he digs and buries the slaughtered bird before him — and this is a tradition from what was heard. He takes cedar wood — and its commandment is that it be an ell long and its width be like a quarter of a foot of the feet of a bed; and not less than a handbreadth of hyssop that does not have an adjunct name; wool dyed red, the weight of which is a shekel, and if he mixed [its color], he disqualified it, like the dying of the aquamarine, which is disqualified by mixing. And all the measures are a law [from Moshe at Sinai] (Eruvin 4a). And he takes the living bird with the three of them; and the four species impede one another (Menachot 27a); and cedar wood or hyssop that have been peeled are disqualified. He ties the hyssop to the cedar wood with a strip of crimson fabric and surrounds them with the tips of the wings and the tip of the tail of the living bird. And he dips the four of them in water that is in the vessel and in the blood that is [in] it; “and sprinkles seven times on the back of the hand of the metsora.” And he sends away the bird. And how does he send it away? If he is standing in the city, he throws it out of the wall (Kiddushin 57b). “He does not face the sea nor the city, but the desert, as it is stated (Leviticus 14:53), ‘to outside the city towards the field’” (Mishnah Negaim 14:2). [If] he sent it and it comes back, he again sends it away — even a hundred times.
וְאַחַר כָּךְ מְגַלֵּחַ הַכֹּהֵן אֶת הַמְּצֹרָע, וְכֵיצַד מְגַלְּחוֹ? מַעֲבִיר תַּעַר עַל בְּשָׂרוֹ הַנִּרְאֶה, וַאֲפִלּוּ בֵּית הַשֶּׁחִי וּבֵית הָעֶרְוָה וּשְׁאָר כָּל הַגּוּף עַד שֶׁיֵּעָשֶׂה כִּדְלַעַת, שֶׁנֶּאֱמַר (שם שם ט) אֶת כָּל שְׂעָרוֹ. אִם כֵּן לָמָּה נֶאֱמַר רֹאשׁוֹ וּזְקָנוֹ וְגַבּוֹת עֵינָיו? לְרַבּוֹת כָּל כַּיּוֹצֵא בָּהֶן וּלְמַעֵט שֵׂעָר שֶׁבְּתוֹךְ הַחֹטֶם לְפִי שֶׁאֵינוֹ נִרְאֶה. וְאַחַר כָּךְ מְכַבֵּס בְּגָדָיו וְטוֹבֵל וְיִטְהַר בְּכָךְ מִלְּטַמֵּא בְּבִיאָה וּמִלְּטַמֵּא בְּמִשְׁכָּב וּמוֹשָׁב וְיִכָּנֵס לִפְנִים מִן הַחוֹמָה. וּמוֹנֶה שִׁבְעַת יָמִים, וְהוּא אָסוּר בְּשִׁבְעַת הַיָּמִים אֵלּוּ בְּתַשְׁמִישׁ הַמִּטָּה, שֶׁנֶּאֱמַר מִחוּץ לְאָהֳלוֹ מְלַמֵּד שֶׁאָסוּר בְּתַשְׁמִישׁ הַמִּטָּה, אֲבָל מְצֹרַעַת מֻתֶּרֶת בְּתַשְׁמִישׁ הַמִּטָּה. כָּל שִׁבְעַת הַיָּמִים אֵלּוּ עֲדַיִן הוּא אַב הַטֻּמְאָה וּמְטַמֵּא אָדָם וְכֵלִים בְּמַגָּע וְאֵינוֹ מְטַמֵּא בְּמַשָּׂא, שֶׁהֲרֵי הוּא אוֹמֵר (שם ט) וְהָיָה בַּיּוֹם הַשְּׁבִיעִי וְגוֹ' וְכִבֶּס בְּגָדָיו, מְלַמֵּד שֶׁהָיָה מְטַמֵּא בְּגָדִים. וּכְשֵׁם שֶׁהָיָה מְטַמֵּא בְּגָדִים בְּמַגָּע, כָּךְ מְטַמֵּא אָדָם בְּמַגָּע, שֶׁכָּל הַמְּטַמֵּא אָדָם מְטַמֵּא בְּגָדִים, וְשֶׁאֵינוֹ מְטַמֵּא אָדָם אֵינוֹ מְטַמֵּא בְּגָדִים (כלים א א). וּבְיוֹם הַשְּׁבִיעִי מְגַלְּחוֹ הַכֹּהֵן תִּגְלַחַת שְׁנִיָּה כְּתִגְלַחַת רִאשׁוֹנָה, וּמְכַבֵּס בְּגָדָיו וְטוֹבֵל וְיִטְהַר מִלְּטַמֵּא אֲחֵרִים, וַהֲרֵי הוּא כְּכָל טְבוּלֵי יוֹם וְאוֹכֵל בַּמַּעֲשֵׂר, הֶעֱרִיב שִׁמְשׁוֹ אוֹכֵל בַּתְּרוּמָה, הֵבִיא כַּפָּרָתוֹ אוֹכֵל בַּקֳּדָשִׁים. שְׁחִיטַת הַצִּפּוֹר וְהַתִּגְלַחַת וְהַהַזָּאָה בַּיּוֹם, וּשְׁאָר כָּל מַעֲשָׂיו בֵּין בַּיּוֹם בֵּין בַּלַּיְלָה. וְאֵלּוּ בָּאֲנָשִׁים וְכָל הַשְּׁאָר אֲפִילּוּ נָשִׁים, וְאֵלּוּ בַּכֹּהֲנִים וְכָל הַשְּׁאָר אֲפִילּוּ עַל יְדֵי יִשְׂרָאֵל. וְאוֹתוֹ כֹּהֵן שֶׁטִּמְּאוֹ מִצְוָה לְטַהֲרוֹ, שֶׁנֶּאֱמַר (שם יג נט) לְטַהֲרוֹ אוֹ לְטַמְּאוֹ. וְיֶתֶר פְּרָטֶיהָ בְּמַסֶּכֶת נְגָעִים.
And afterwards, the priest shaves the metsora. And how does he shave him? He passes the razor over his visible flesh — and even [on] the underarm and the pubic area and all the rest of the body — until he becomes [smooth] like a gourd, as it is stated (Leviticus 14:9), “all of his hair.” If so, why does it state, “his head, his beard, and his eyebrows?” To include everything that is like them and to exclude hair that is in the nose, since it is not seen. And afterwards he washes his clothes and immerses, and is purified with this from passing on impurity from his resting and sitting [upon something]; and he can come inside the [city] wall. And he counts seven days; and during those seven days, he is prohibited in sexual relations, as it is stated, “outside of his tent” — teaching he is forbidden in sexual relations. But a metsora’at is permitted in sexual relations. All of these seven days, he is still a source of impurity and renders a person and vessels impure with touch, but he does render impure with carrying — as behold it states (Leviticus 14:9), “And it shall be on the seventh day, etc. and he shall wash his clothes” — teaching that he was rendering clothes impure. And [just] like he was rendering clothes impure, so [too] was he rendering a man impure with touch — since all that renders a person impure, renders clothes impure; and all that does not render a person impure, does not render clothes impure (Mishnah Kelim 1:1). And on the seventh day, the priest shaves him a second [time] like the first shaving. And [the metsora] washes his clothes and immerses and is purified from rendering others impure. And behold he is like all who have immersed during the day, and can eat from the tithe; when his sun sets, he can eat from the priestly tithe; [and] when he brings his atonement, he can eat from consecrated foods. The slaughter of the bird, the shaving and the sprinkling are during the day, but all the other procedures are whether during the day or during the night. These [three things] are with men, but all the rest are even with women. These are with priests, but all the rest are even through an Israelite. And it is a commandment for the same priest who rendered him impure [to render him pure, as it is stated (Leviticus 13:59)], “to render him pure or to render him impure.” And the rest of its details are in Tractate Negaim.
וְנוֹהֶגֶת טַהֲרָה זוֹ בְּכָל מָקוֹם וּבְכָל זְמַן שֶׁיֵּשׁ כֹּהֵן חָכָם בִּנְגָעִים, כֵּן פֵּרֵשׁ הָרַמְבַּ"ם זִכְרוֹנוֹ לִבְרָכָה, וְכֵן רָאִיתִי בַּסִּפְרָא. וְעוֹבֵר עָלֶיהָ וְלֹא עֲשָׂאָהּ כַּמִּשְׁפָּט, בִּטֵּל עֲשֵׂה.
And this purification is practiced in every place and at all times that there is a priest that is wise about ailments. So did Rambam, may his memory be blessed, explain (and so did I see in Sifra). And one who transgresses it and did not do it like its statute, has violated a positive commandment.