הלכה אויף במדבר 18:21

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.