Numbers 18:17
But the firstling of a cow, or the firstling of a sheep, or the firstling of a goat, thou shalt not redeem; they are holy: thou shalt sprinkle their blood upon the altar, and shalt burn their fat for an offering made by fire, for a sweet savour unto the LORD.
But the firstling of a cow, or the firstling of a sheep, or the firstling of a goat, thou shalt not redeem,.... That is, shalt not take the redemption price for them, but the creatures themselves; which they, the priests, were to take for their own use:
they are holy; separated to the Lord, and therefore not to be used in common by men, but were sacred to the Lord, or became the property of his priests; see Deuteronomy 15:19; how they were to be made use of follows:
thou shalt sprinkle their blood upon the altar; for they were to be sacrificed, and their blood used as in other sacrifices:
and shalt burn their fat for an offering made by fire; for a sweet savour unto the Lord; as the fat of other sacrifices was, and particularly of the peace offerings, which were wholly eaten otherwise, Leviticus 7:31.