The best of it; implying, that if they neglected this duty, they sinned in the use of such unhallowed food. Neither shall ye pollute the holy things, as you will do, if you abuse their holy offerings, by reserving that entirely to yourselves which they offer to God to be disposed as he hath appointed, to wit, part to you, and part to the priests.
Related Commentaries of Numbers 18:32
Numbers 18:32
32 And ye shall bear no sin by reason of it, when ye have heaved from it the best of it: neither shall ye pollute the holy things of the children of Israel, lest ye die.