Canaan was the father of ¹  Sidon his firstborn, ²  Heth, ³ 

Canaan was the father of Sidon – his firstborn – and Heth,

From the Shilonites: Asaiah the firstborn and his sons.

the firstborn Isshiah from Rehabiah and the sons of Rehabiah,

The sons of Jerahmeel, Hezron’s firstborn, were Ram, the firstborn, Bunah, Oren, Ozem, and Ahijah.

because all the firstborn are mine. When I destroyed ¹  all the firstborn in the land of Egypt, I set apart for myself all the firstborn in Israel, both man and beast. They belong to me. I am the Lord.” ² 

The firstborn of every womb which they present to the Lord, whether human or animal, will be yours. Nevertheless, the firstborn sons you must redeem, ¹  and the firstborn males of unclean animals you must redeem.

You must set apart ¹  for the Lord your God every firstborn male born to your herds and flocks. You must not work the firstborn of your bulls or shear the firstborn of your flocks.

“Every firstborn of the womb ¹  belongs to me, even every firstborn ²  of your cattle that is a male, ³  whether ox or sheep.

Hosah, one of the descendants of Merari, had sons: The firstborn Shimri (he was not actually the firstborn, but his father gave him that status),

Uz the firstborn, his brother Buz, Kemuel (the father of Aram), ¹ 

His father Isaac asked, ¹  “Who are you?” “I am your firstborn son,” ²  he replied, “Esau!”

Judah acquired ¹  a wife for Er his firstborn; her name was Tamar.

You must say ¹  to Pharaoh, ‘Thus says ²  the Lord, “Israel is my son, my firstborn, ³ 

and all the firstborn in the land of Egypt will die, from the firstborn son of Pharaoh ¹  who sits on his throne, to the firstborn son of the slave girl who is at her hand mill, and all the firstborn of the cattle.

¹ It happened ²  at midnight – the Lord attacked all the firstborn in the land of Egypt, from the firstborn of Pharaoh who sat on his throne to the firstborn of the captive who was in the prison, and all the firstborn of the cattle.

When Pharaoh stubbornly refused ¹  to release us, the Lord killed all the firstborn in the land of Egypt, from the firstborn of people to the firstborn of animals. ²  That is why I am sacrificing ³  to the Lord the first male offspring of every womb, but all my firstborn sons I redeem.’

So Moses numbered all the firstborn males among the Israelites, as the Lord had commanded him.

So I have taken the Levites instead of all the firstborn sons among the Israelites.

Jesse was the father of Eliab, his firstborn; Abinadab was born second, Shimea third,