The sons of Ram, Jerahmeel’s firstborn, were Maaz, Jamin, and Eker.

The sons of Reuben, Israel’s firstborn – (Now he was the firstborn, but when he defiled his father’s bed, ¹  his rights as firstborn were given to the sons of Joseph, Israel’s son. So Reuben is not listed as firstborn in the genealogical records. ² 

The sons of Reuben, Israel’s firstborn: Hanoch, Pallu, Hezron, and Carmi.

The sons of Samuel: Joel the firstborn ¹  and Abijah the second oldest.

Benjamin was the father of Bela, his firstborn; Ashbel was born second, Aharah ¹  third,

His firstborn son was Abdon, followed by Zur, Kish, Baal, ¹  Nadab,

The sons of his brother Eshek: Ulam was his firstborn, Jeush second, and Eliphelet third.

His firstborn son was Abdon, followed by Zur, Kish, Baal, Ner, Nadab,

Meshelemiah’s sons: The firstborn Zechariah, the second Jediael, the third Zebadiah, the fourth Jathniel,

He struck down all the firstborn in their land, the firstfruits of their reproductive power. ¹ 

He struck down the firstborn of Egypt, including both men and animals.

to the one who struck down the firstborn of Egypt, for his loyal love endures,

“‘Surely no man may consecrate a firstborn that already belongs to the Lord as a firstborn among the animals; whether it is an ox or a sheep, it belongs to the Lord. ¹ 

And take ¹  the Levites for me – I am the Lord – instead of all the firstborn males among the Israelites, and the livestock of the Levites instead of all the firstborn of the livestock of the Israelites.”

For all the firstborn males among the Israelites are mine, both humans and animals; when I destroyed ¹  all the firstborn in the land of Egypt I set them apart for myself.

In the day he divides his inheritance ¹  he must not appoint as firstborn the son of the favorite wife in place of the other ²  wife’s son who is actually the firstborn.

The tribe of Manasseh, Joseph’s firstborn son, was also allotted land. ¹  The descendants of Makir, Manasseh’s firstborn and the father of Gilead, received land, for they were warriors. ²  They were assigned Gilead and Bashan. ³ 

“It is not our custom here,” ¹  Laban replied, “to give the younger daughter in marriage ²  before the firstborn.

The sons of Leah were Reuben, Jacob’s firstborn, as well as Simeon, Levi, Judah, Issachar, and Zebulun.

But Er, Judah’s firstborn, was evil in the Lord’s sight, so the Lord killed him.