Numbers 18:25-29

GOD spoke to Moses: “Speak to the Levites. Tell them, When you get the tithe from the People of Israel, the inheritance that I have assigned to you, you must tithe that tithe and present it as an offering to GOD. Your offerings will be treated the same as other people’s gifts of grain from the threshing floor or wine from the wine vat. This is your procedure for making offerings to GOD from all the tithes you get from the People of Israel: give GOD’s portion from these tithes to Aaron the priest. Make sure that GOD’s portion is the best and holiest of everything you get.