American Standard Version (ASV):
but he shall acknowledge the first-born, the son of the hated, by giving him a double portion of all that he hath; for he is the beginning of his strength; the right of the first-born is his.
King James Version (KJV):
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.