Numbers 18:21

"And unto the children 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. And henceforth the children of Israel shall not come nigh the tent of meeting, lest they bear sin, and die. But the Levites shall do the service of the tent of meeting, and they shall bear their iniquity: it shall be a statute forever throughout your generations; and among the children of Israel they shall have no inheritance. For the tithe of the children of Israel, which they offer as a heave-offering unto Jehovah, I have given to the Levites for an inheritance: therefore I have said unto them, Among the children of Israel they shall have no inheritance."

(See Numbers 18:1 for a comment on "bear sin, or bear iniquity.")

"The payment of tithes to the Levites is recognized in Nehemiah 10:37,12:44, but here for the first time assigned to them as theirs."[18] Carson mentioned a "contradiction" in this with Deuteronomy 14:22-29, where for two years the tithes were eaten by the worshippers and the Levites.[19] "Contradiction," however, is far too strong a word for the variation. As we have seen, there were Divine adjustments to accommodate the extremely unusual circumstances of the conquest. Another instance is seen in Joshua, where the ark preceded the people into the Jordan, whereas, it was usually at the center of the camp of Israel.

The tithe was an ancient custom recognized by people of the greatest antiquity. Abraham paid tithes to Melchizedek (Genesis 14), and Jacob vowed to give the tithe of all his possessions (Genesis 28:20-22). The N.T. states that "There he (Jesus) receiveth them (tithes)" (Hebrews 7:8).