Numbers 18:26-28 Evangelical Heritage Version (EHV)
26 to speak to the Levites and tell them this:
When you receive from the Israelites the tithe, which I have given to you as your possession, you will lift up an elevated offering from it for the Lord, a tenth of the tithe. 27 Your elevated offering will be credited to you, as if it were grain from the threshing floor and abundance from the winepress. 28 In this way you also are to lift up an elevated offering for the Lord from every one of the tithes which you receive from the Israelites. From the tithes, you will give the elevated offering for the Lord to Aaron the priest.