כִּ֞י אֶת־מַעְשַׂ֣ר בְּנֵֽי־יִשְׂרָאֵ֗ל אֲשֶׁ֨ר יָרִ֤ימוּ לַֽיהוָה֙ תְּרוּמָ֔ה נָתַ֥תִּי לַלְוִיִּ֖ם לְנַחֲלָ֑ה עַל־כֵּן֙ אָמַ֣רְתִּי לָהֶ֔ם בְּתוֹךְ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל לֹ֥א יִנְחֲל֖וּ נַחֲלָֽה׃ (פ)
Car la dîme que les enfants d’Israël prélèveront pour le Seigneur, comme tribut, je la donne aux Lévites comme patrimoine; c’est pourquoi je leur déclare qu’ils n’auront point de patrimoine entre les enfants d’Israël."
Mishneh Torah, Gifts to the Poor
And this is the system of gift-offerings and tithes: After one has harvested the seeds of the earth or gathered the fruit of the trees and has completed one's labor, one must separate out one-fiftieth, and this is called the terumah gedolah [the "great gift-offering"], and one gives it to a priest. About this it is said in the Torah, (Deut. 18:4) You shall also give him the first fruits of your new grain and wine and oil. Afterwards, one separates from the remainder one-tenth, and this is called ma'asér rishon [the "first tithe"], and one gives it to a Levite. About this it is said in the Torah, (Num. 18:24) For it is the tithes set aside by the Israelites [as a gift to the LORD hat I give to the Levites as their share], and (Num. 18:21) To the Levites I hereby give all the tithes in Israel.
Mishneh Torah, Positive Mitzvot
To set apart the tithe of the corn for the Levites, as it is said, “And all the tithe of the land, whether of the seed of the land or of the fruit of the tree, (is the Lord’s)” (Lev. 27:30).
Sefer HaChinukh
The commandment of the first tithe: That the Children of Israel were obligated to give one-tenth part of the seed of the Land to the Levites, as it is stated (Numbers 18:24), “For it is the tithes of the Children of Israel that they will give to the Lord that I give to the Levites as a gift.” And it is stated in the Order of Eem Bechukotai (Leviticus 27:30), “And all of the tithe of the Land, etc. it is for the Lord.” And that is what is called the first tithe (maaser rishon).