Deuteronomy 21:17
But he shall acknowledge the son of the hated for the firstborn, and shall give him a double portion of all he hath: for this is the first of his children, and to him are due the first birthrights.But he shall acknowledge the son of the hated for the firstborn, and shall give him a double portion of all he hath: for this is the first of his children, and to him are due the first birthrights.