Numbers 18:20-25

²⁰And the Lord said to Aaron: You shall possess nothing in their land, neither shall you have a portion among them: I am thy portion and inheritance in the midst of the children of Israel.

²¹And I have given to the sons of Levi all the tithes of Israel for a possession for the ministry wherewith they serve me in the tabernacle of the covenant:

²²That the children of Israel may not approach any more to the tabernacle, nor commit deadly sin,

²³But only the sons of Levi may serve me in the tabernacle, and bear the sins of the people. It shall be an everlasting ordinance in your generations. They shall not possess any other thing,

²⁴But be content with the oblation or tithes, which I have separated for their uses and necessities.

²⁵And the Lord spoke to Moses, saying: