“And God spoke to Moshe at mount Sinai, saying: Speak to the children of Israel and say unto them, when you enter the land which I give you, you shall let the land rest a Sabbath unto Hashem.” (Vayikra, 25:1–2) Here God promises Israel that when they come to the land of Israel their hearts will be at peace. “Land” teaches of the heart. This is “let the land rest,” that their hearts shall be at peace.
וַיְדַבֵּר ה' אֶל מֹשֶׁה בְּהַר סִינַי לֵאמֹר וְכוּ' כִּי תָבֹאוּ וְכוּ' וְשָׁבְתָה הָאָרֶץ שַׁבָּת לַה'. וְהוּא שֶׁהִבְטִיחַ הַש"י לְיִשְׂרָאֵל כְּשֶׁיָּבוֹאוּ לְאֶרֶץ יִשְׂרָאֵל יְהִי לִבָּם בְּנַיְיחָא כִּי אֶרֶץ מוֹרָה עַל הַלֵּב, וְזֶה "וְשָׁבְתָה הָאָרֶץ" שֶׁיִּהְיֶה לִבָּם בְּנַיְיחָא.
“And God spoke to Moshe at mount Sinai, saying: Speak to the children of Israel and say unto them, when you enter the land which I give you, you shall let the land rest a Sabbath unto Hashem.” (Vayikra, 25:1–2)
Here God promises Israel that when they come to the land of Israel their hearts will be at peace. “Land” teaches of the heart. This is “let the land rest,” that their hearts shall be at peace.