Numbers 18:26-28

Amplified Bible

²⁶ “Moreover, you shall speak to the Levites and say to them, ‘When you take from the Israelites the tithe which I have given to you from them as your inheritance, then you shall present an offering from it to the Lord, a tithe of the tithe [paid by the people]. ²⁷ Your offering shall be credited to you as the grain from the threshing floor or as the full produce from the wine vat. 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.