Numbers 18:28-30

Amplified Bible

²⁸ Likewise you shall also present an offering to the Lord from all your tithes, which you receive from the Israelites; and from it you shall give the Lord’s offering to Aaron the priest. ²⁹ Out of all your gifts, you shall present every offering due to the Lord, from all the best of it, even the sacred part from them.’ ³⁰ Therefore you shall say to them, ‘When you have offered the best from it, then the rest shall be credited to the Levites as the product of the threshing floor, and as the product of the wine vat.