John Wesley on Numbers 18:2

Unto thee - About sacrifices and offerings and other things, according to the rules I have prescribed them. The Levites are said to minister to Aaron here, to the church, Num 16:9, and to God, Deu 10:8. They shall not contend with thee for superiority, as they have done, but shall be subordinate to thee. Thy sons with thee - Or, both to thee, and to thy sons with thee: Which translation may seem to be favoured by the following words, before the tabernacle, which was the proper place where the Levites ministered. Besides, both the foregoing words, and the two following verses, entirely speak of the ministry of the Levites, and the ministry of the priests is distinctly spoken of, Nu 18:5.