Numbers 18:24-26

New Revised Standard Version Catholic Edition

²⁴ because I have given to the Levites as their portion the tithe of the Israelites, which they set apart as an offering to the Lord. Therefore I have said of them that they shall have no allotment among the Israelites.

²⁵ Then the Lord spoke to Moses, saying: ²⁶ You shall speak to the Levites, saying: When you receive from the Israelites the tithe that I have given you from them for your portion, you shall set apart an offering from it to the Lord, a tithe of the tithe.