Numbers 18:26
“Speak to the Levites and tell them: When you receive from the Israelites the tenth that I have given you as your inheritance, you must present part of it as an offering to the Lord—a tenth of the tenth.
Nehemiah 10:38
A priest of Aaronic descent must accompany the Levites when they collect the tenth,
Numbers 18:21
“Look, I have given the Levites every tenth in Israel as an inheritance in return for the work they do, the work of the tent of meeting.