'First born' in the Bible

The descendants of Reuben, the firstborn of Israel: according to their family records by their clans and their ancestral houses, counting one by one the names of every male 20 years old or more, everyone who could serve in the army,

And these are the names of the sons of Aaron; Nadab the firstborn, and Abihu, Eleazar, and Ithamar.

And I, behold, I have taken the Levites from among the children of Israel instead of all the firstborn that openeth the matrix among the children of Israel: therefore the Levites shall be mine;

Because all the firstborn are mine; for on the day that I smote all the firstborn in the land of Egypt I hallowed unto me all the firstborn in Israel, both man and beast: mine shall they be: I am the LORD.

And the LORD said unto Moses, Number all the firstborn of the males of the children of Israel from a month old and upward, and take the number of their names.

And thou shalt take the Levites for me (I am the LORD) instead of all the firstborn among the children of Israel; and the cattle of the Levites instead of all the firstlings among the cattle of the children of Israel.

And Moses numbered, as the LORD commanded him, all the firstborn among the children of Israel.

And all the firstborn males by the number of names, from a month old and upward, of those that were numbered of them, were twenty and two thousand two hundred and threescore and thirteen.

Take the Levites instead of all the firstborn among the children of Israel, and the cattle of the Levites instead of their cattle; and the Levites shall be mine: I am the LORD.

And for those that are to be redeemed of the two hundred and threescore and thirteen of the firstborn of the children of Israel, which are more than the Levites;

Of the firstborn of the children of Israel took he the money; a thousand three hundred and threescore and five shekels, after the shekel of the sanctuary:

For they are wholly given unto me from among the children of Israel; instead of such as open every womb, even instead of the firstborn of all the children of Israel, have I taken them unto me.

For all the firstborn of the children of Israel are mine, both man and beast: on the day that I smote every firstborn in the land of Egypt I sanctified them for myself.

And I have taken the Levites for all the firstborn of the children 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.

“However, you must not redeem the firstborn of an ox, a sheep, or a goat; they are holy. You are to sprinkle their blood on the altar and burn their fat as a fire offering for a pleasing aroma to the Lord.

Reuben was the firstborn of Israel.Reuben’s descendants:the Hanochite clan from Hanoch;the Palluite clan from Pallu;

For the Egyptians buried all their firstborn, which the LORD had smitten among them: upon their gods also the LORD executed judgments.