Matthew Poole and continuators on Numbers 18:24

24 But the tithes of the children of Israel, which they offer as an heave-offering unto the LORD , I have given to the Levites to inherit: therefore I have said unto them, Among the children of Israel they shall have no inheritance.

(i. e.) As a rent-charge or an acknowledgment that they have and hold all their lands and the fruits of it from Gods bounty. Note that the word heave-offering, which is for the most part understood of a particular kind of offerings heaved or lifted up to the Lord, is here used for any offering in general, as before, ver. 8.