14 Every devoted thing in Israel shall be yours. 15 The first issue of the womb of all creatures, human and animal, which is offered to the Lord, shall be yours; but the firstborn of human beings you shall redeem, and the firstborn of unclean animals you shall redeem. 16 Their redemption price, reckoned from one month of age, you shall fix at five shekels of silver, according to the shekel of the sanctuary (that is, twenty gerahs). 17 But the firstborn of a cow, or the firstborn of a sheep, or the firstborn of a goat, you shall not redeem; they are holy. You shall dash their blood on the altar, and shall turn their fat into smoke as an offering by fire for a pleasing odor to the Lord; 18 but their flesh shall be yours, just as the breast that is elevated and as the right thigh are yours. 19 All the holy offerings that the Israelites present to the Lord I have given to you, together with your sons and daughters, as a perpetual due; it is a covenant of salt forever before the Lord for you and your descendants as well.
Matthew Henry's Commentary on Numbers 18:14-19
Commentary on Numbers 18:8-19
(Read Numbers 18:8-19)
All believers are spiritual priests, and God has promised to take care of them. Godliness has the promise of the life that now is. And from the provision here made for the priests, the apostle shows that it is the duty of christian churches to maintain their ministers. Scandalous maintenance makes scandalous ministers. The priests were to be wholly devoted to their ministry, not diverted from it, or disturbed in it, by worldly care or business. Also, that they might be examples of living by faith, not only in God's providence, but in his ordinances. The best should be offered for the first-fruits unto the Lord. Those who think to save, by putting God off with the refuse, deceive themselves, for God is not mocked.