Deuteronomy 21:17
But he shall acknowledge the first-born, the son of the one regarded inferior, by giving him a double portion of all that he has, for he is the beginning of his strength. The right of the first-born is his.
Genesis 49:3
Reuben, thou are my firstborn, my might, and the beginning of my strength, the pre-eminence of dignity, and the pre-eminence of power.
Genesis 25:31-34
And Jacob said, First sell me thy birthright.
Genesis 25:5-6
And Abraham gave all that he had to Isaac.
1 Chronicles 5:1-2
And the sons of Reuben the first-born of Israel (for he was the first-born, but, inasmuch as he defiled his father's couch, his birthright was given to the sons of Joseph the son of Israel, and so the genealogy is not to be reckone
Psalm 105:36
He also smote all the firstborn in their land, the chief of all their strength.