'First born' in the Bible

And you shall say unto Pharaoh, Thus says the LORD, Israel is my son, even my firstborn:

And I say unto you, Let my son go, that he may serve me: and if you refuse to let him go, behold, I will slay your son, even your firstborn.

These are the heads of their fathers' houses: The sons of Reuben the firstborn of Israel; Hanoch, and Pallu, Hezron, and Carmi: these are the families of Reuben.

And all the firstborn in the land of Egypt shall die, from the firstborn of Pharaoh that sits upon his throne, even unto the firstborn of the maidservant that is behind the mill; and all the firstborn of beasts.

For I will pass through the land of Egypt this night, and will smite all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the LORD.

And it came to pass, that at midnight the LORD smote all the firstborn in the land of Egypt, from the firstborn of Pharaoh that sat on his throne to the firstborn of the captive that was in the dungeon; and all the firstborn of cattle.

Sanctify unto me all the firstborn, whatsoever opens the womb among the children of Israel, both of man and of beast: it is mine.

And every firstling of a donkey you shall redeem with a lamb; and if you will not redeem it, then you shall break its neck: and all the firstborn of man among your children shall you redeem.

And it came to pass, when Pharaoh refused to let us go, that the LORD slew all the firstborn in the land of Egypt, both the firstborn of man, and the firstborn of beast: therefore I sacrifice to the LORD all that opens the womb, being males; but all the firstborn of my children I redeem.

You shall not delay to offer the first of your ripe fruits, and of the outflow of your presses: the firstborn of your sons shall you give unto me.

But the firstling of a donkey you shall redeem with a lamb: and if you redeem it not, then shall you break its neck. All the firstborn of your sons you shall redeem. And none shall appear before me empty.