Deuteronomy 21:17

But he shall acknowledge the firstborn son of the disliked [wife] {by giving} him a double portion of {all that he has}, for he [is] the firstfruit of his vigor; to him [is] the legal claim of the birthright.

Genesis 49:3

Reuben, you [are] my firstborn, my strength, and the firstfruit of my vigor, excelling in rank and excelling in power.

Genesis 25:31-34

Then Jacob said, "Sell me your birthright {first}."

Genesis 25:5-6

And Abraham gave all he had to Isaac.

1 Chronicles 5:1-2

The sons of Reuben the firstborn of Israel (for he was the firstborn, but when he defiled the couch of his father, his birthright was given to the sons of Joseph, the son of Israel, so that he was not enrolled in the genealogy as the firstborn,

Psalm 105:36

And he struck down all [the] firstborn in their land, [the] first of all their virility.

Treasury of Scripture Knowledge

Summary

But he shall acknowledge the son of the hated for the firstborn, by giving him a double portion of all that he hath: for he is the beginning of his strength; the right of the firstborn is his.

The beginning

The right

Bible References

By giving

Genesis 25:5
And Abraham gave all he had to Isaac.
1 Chronicles 5:1
The sons of Reuben the firstborn of Israel (for he was the firstborn, but when he defiled the couch of his father, his birthright was given to the sons of Joseph, the son of Israel, so that he was not enrolled in the genealogy as the firstborn,

The beginning

Genesis 49:3
Reuben, you [are] my firstborn, my strength, and the firstfruit of my vigor, excelling in rank and excelling in power.
Psalm 105:36
And he struck down all [the] firstborn in their land, [the] first of all their virility.

The right

Genesis 25:31
Then Jacob said, "Sell me your birthright {first}."