Numbers 18:22-25

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: