And Reuben—who had not consented to, but had been altogether unable to prevent, the wickedness of his brethren (Genesis 37:22, Genesis 37:29)—answered them, saying, Spake I not unto you, saying, Do not sin against the child (or lad); and ye would not hear?
therefore, behold, also his blood is required—literally, and also his blood, behold it is required. This was in accordance with the Noachic law against bloodshed (Genesis 9:5), with which it is apparent that Jacob's sons were acquainted.