1 Samuel 18:17 - 18:19
17 Then Saul said to David, “Here is my older daughter Merab; I will give her to you as a wife; only be a man of valor for me and fight Yahweh’s battles.” For Saul thought, “My hand shall not be against him, but let the hand of the Philistines be against him.” 18 But David said to Saul, “Who am I, and what is my life or my father’s family in Israel, that I should be the king’s son-in-law?” 19 So it happened at the time when Merab, Saul’s daughter, should have been given to David, that she was given to Adriel the Meholathite as a wife.