'Firstling' in the Bible

and thou hast taken the Levites for Me (I am Jehovah), instead of every first-born among the sons of Israel, and the cattle of the Levites instead of every firstling among the cattle of the sons of Israel.'

Every thing that openeth the matrix in all flesh, which they bring unto the LORD, whether it be of men or beasts, shall be thine: nevertheless the firstborn of man shalt thou surely redeem, and the firstling of unclean beasts shalt thou redeem.

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.