To not testify falsely: To not testify [with] false testimony, as it states (Exodus 20:13), “You shall not bear false witness against your neighbor.” And it is repeated in another place in another negative commandment — the “vain witness.”
The root of this commandment is revealed, as falsehood is “disgraceful and vile” in the eye of any intelligent one; also because the world stands upon true testimony, since all [types] of arguments can be [settled by] the testimony of people. And, if so, false testimony is a cause for the destruction of the world.
The laws of the commandment — for example, from whom do we accept testimony (Mishneh Torah, Laws of Testimony 9:1) and from whom do we not accept [it]; what is it that disqualifies people from testifying; how is [the process] of accepting testimony; that there are people that do not testify for anyone, due to their great stature; examination of the testimony and the interrogation; the differences between testimony in financial cases and capital cases; the difference between investigation and corroboration; the difference between [written] testimony and oral; and the rest of its many details are elucidated in Sanhedrin and in [other places] in the Gemara. (See Tur, Choshen Mishpat 38.)
And [it] is practiced in every place and at all time by males, but not by females. As women are not [included] in the category of testimony, since testimony requires focus and much concentration. And the verse put a limit on the punishment of the one who transgresses this negative prohibition and testifies falsely against his fellow, to do unto him as he thought to do his fellow (Deuteronomy 19:19). And there are also lashes for it (Makkot 2a). And it is also elucidated there in Sanhedrin.
שֶׁלֹּא לְהָעִיד בְּשֶׁקֶר – שֶׁלֹּא לְהָעִיד עֵדוּת שֶׁקֶר, שֶׁנֶּאֱמַר (שמות כ יג) לֹא תַעֲנֶה בְרֵעֲךָ עֵד שָׁקֶר, וְנִכְפְּלָה בְּמָקוֹם אַחֵר בְּלָאו אַחֵר עֵד שָׁוְא.
To not testify falsely: To not testify [with] false testimony, as it states (Exodus 20:13), “You shall not bear false witness against your neighbor.” And it is repeated in another place in another negative commandment — the “vain witness.”
שֹׁרֶשׁ מִצְוָה זוֹ נִגְלֶה, כִּי הַשֶּׁקֶר נִמְאָס וְנֶאֱלָח לְעֵין כָּל מַשְׂכִּיל, גַּם כִּי בְּעֵדוּת אֱמֶת הָעוֹלָם עוֹמֵד, שֶׁכָּל דִּבְרֵי רִיבוֹת בְּנֵי אָדָם מִתְבַּטְּלִים בְּעֵדוּת אֲנָשִׁים. וְאִם כֵּן עֵדוּת שֶׁקֶר סִבָּה לְחֻרְבַּן הַיִּשּׁוּב.
The root of this commandment is revealed, as falsehood is “disgraceful and vile” in the eye of any intelligent one; also because the world stands upon true testimony, since all [types] of arguments can be [settled by] the testimony of people. And, if so, false testimony is a cause for the destruction of the world.
דִּינֵי הַמִּצְוָה, כְּגוֹן מִמִּי מְקַבְּלִין עֵדוּת (רמב"ם עדות ט א') וּמִמִּי אֵין מְקַבְּלִין, וּבַמֶּה יִפָּסְלוּ בְּנֵי אָדָם לְהָעִיד, וְכֵיצַד קַבָּלַת הָעֵדוּת, וְכִי יֵשׁ בְּנֵי אָדָם שֶׁאֵין מְעִידִין לְכָל אָדָם מֵרֹב מַעֲלָתָן, וּדְרִישַׁת הָעֵדוּת וְהַחֲקִירָה, וְהַחִלּוּקִין שֶׁבֵּין עֵדוּת מָמוֹן לְעֵדוּת נְפָשׁוֹת, וְהַחִלּוּק שֶׁבֵּין דְּרִישָׁה לִבְדִיקָה, וְהַחִלּוּק שֶׁבֵּין עֵדוּת בִּשְׁטָר לִבְעַל פֶּה, וְיֶתֶר רֻבֵּי פְּרָטֶיהָ מְבֹאָרִין בְּסַנְהֶדְרִין (יח א, לב א, מב א) וּבִמְקוֹמוֹת בגמ' (ח"ה לח).
The laws of the commandment — for example, from whom do we accept testimony (Mishneh Torah, Laws of Testimony 9:1) and from whom do we not accept [it]; what is it that disqualifies people from testifying; how is [the process] of accepting testimony; that there are people that do not testify for anyone, due to their great stature; examination of the testimony and the interrogation; the differences between testimony in financial cases and capital cases; the difference between investigation and corroboration; the difference between [written] testimony and oral; and the rest of its many details are elucidated in Sanhedrin and in [other places] in the Gemara. (See Tur, Choshen Mishpat 38.)
וְנוֹהֶגֶת בְּכָל מָקוֹם וּבְכָל זְמַן בִּזְכָרִים אֲבָל לֹא בִּנְקֵבוֹת, שֶׁאֵין הַנָּשִׁים בְּתוֹרַת עֵדוּת, שֶׁהָעֵדוּת צָרִיךְ כִּוּוּן וְיִשּׁוּב הַדַּעַת הַרְבֵּה. וְהָעוֹבֵר עַל לָאו זֶה וְהֵעִיד עֵדוּת שֶׁקֶר בַּחֲבֵרוֹ, שָׂם הַכָּתוּב (דברים יט יט) גְּבוּל עָנְשׁוֹ לַעֲשׂוֹת לוֹ כַּאֲשֶׁר חָשַׁב לַעֲשׂוֹת לַחֲבֵרוֹ, וְיֵשׁ בּוֹ מַלְקוּת (מכות ב, א) כְּמוֹ כֵן. וְשָׁם בְּסַנְהֶדְרִין גַּם כֵּן מִתְבָּאֵר.
And [it] is practiced in every place and at all time by males, but not by females. As women are not [included] in the category of testimony, since testimony requires focus and much concentration. And the verse put a limit on the punishment of the one who transgresses this negative prohibition and testifies falsely against his fellow, to do unto him as he thought to do his fellow (Deuteronomy 19:19). And there are also lashes for it (Makkot 2a). And it is also elucidated there in Sanhedrin.