Numbers 18:32

They would load no sin upon themselves by so doing (see Lev 19:17), if they only lifted off the best as tithe (for the priest), and did not desecrate the holy gifts, sc., by eating in all kinds of places, which was not allowed, according to Num 18:10, with regard to the most holy gifts. These regulations concerning the revenues of the priests and Levites were in perfect accordance with the true idea of the Israelitish kingdom of God. Whereas in heathen states, where there was an hereditary priestly caste, that caste was generally a rich one, and held a firm possession in the soil (in Egypt, for example; see at Gen 47:22), the Levites received no hereditary landed property in the land of Israel, but only towns to dwell in among the other tribes, with pasturage for their cattle (ch. 35), because Jehovah, the God of Israel, would be their inheritance. In this way their earthly existence as based upon the spiritual ground and soil of faith, in accordance with the calling assigned them to be the guardians and promoters of the commandments, statutes, and rights of Jehovah; and their authority and influence among the people were bound up with their unreserved surrender of themselves to the Lord, and their firm reliance upon the possession of their God. Now, whilst this position was to be a constant incitement to the Levites to surrender themselves entirely to the Lord and His service, it was also to become to the whole nation a constant admonition, inasmuch as it was a prerogative conferred upon them by the Lord, to seek the highest of all good in the possession of the Lord, as its portion and inheritance. - The revenue itself, however, which the Lord assigned to the Levites and priests, as His servants, consisting of the tenths and first-fruits, as well as certain portions of…

Aaron being now fully established in the priesthood abundantly to his own satisfaction, and to the satisfaction of the people (which was the good that God brought out of the evil opposition made to him), in this chapter God gives him full instructions concerning his office or rather repeats those which he had before given him. He tells him, I. What must be his work and the care and charge committed to him, and what assistance he should have the Levites in that work (Num 18:1-7). II. What should be his and the Levites' wages for this work. 1. The perquisites or fees peculiar to the priests (Num 18:8-19). 2. The settled maintenance of the Levites (Num 18:20-24). III. The portion which must be paid to the priests out of the Levites' maintenance (Num 18:25-32). Thus every one knew what he had to do, and what he had to live upon.

18:32 The food tithes had a sacred origin as holy gifts of the people of Israel; they were not to turn these gifts into something common by neglecting to give a tithe to the priests.