thy sister] By both parents, or by the mother onely; (for of sisters by a stepmother order is set down ver. 11.) born in marriage, or out of marriage, (by fornication, as a bastard;) yet it was not generally so taken, for Thamar thought, that David would have given her for a wife to Amnon, if he had made request for her unto his father, 2 Samuel 13:13.