26 Moreover thou shall speak to the Levites, and say to them, When ye take from the sons of Israel the tithe which I have given you from them for your inheritance, then ye shall offer up a heave offering of it for LORD, a tithe of the tithe.
Numbers 18:26 Cross References - ACV
Numbers 18:21
21 And to the sons of Levi, behold, I have given all the tithe in Israel for an inheritance, in return for their service which they serve, even the service of the tent of meeting.
Nehemiah 10:38
38 And the priest the son of Aaron shall be with the Levites when the Levites take tithes. And the Levites shall bring up the tithe of the tithes to the house of our God, to the chambers, into the treasure-house.