Genesis 49:3

49:3 Reuben, you are my firstborn,

my might and the beginning of my strength,

outstanding in dignity, outstanding in power.

Exodus 4:22-23

4:22 You must say to Pharaoh, ‘Thus says the Lord, “Israel is my son, my firstborn, 4:23 and I said to you, ‘Let my son go that he may serve me,’ but since you have refused to let him go, I will surely kill your son, your firstborn!”’”

Romans 8:29

8:29 because those whom he foreknew he also predestined to be conformed to the image of his Son, that his Son would be the firstborn among many brothers and sisters.

Hebrews 12:23

12:23 and congregation of the firstborn, who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous, who have been made perfect,