1 Samuel 18:19-29

19 But when the time came to give Merab, Saul's daughter, to David, she was given to Adriel of Meholath.
20 And Saul's daughter Michal was in love with David: and Saul had word of it and was pleased.
21 And Saul said, I will give her to him, so that she may be a cause of danger to him, and so that the hands of the Philistines may be against him. So Saul said to David, Today you are to become my son-in-law for the second time.
22 And Saul gave his servants orders saying, Have talk with David secretly and say to him, See how the king has delight in you, and how you are loved by all his servants: then be the king's son-in-law.
23 And Saul's servants said these things to David. And David said, Does it seem to you a small thing to be the king's son-in-law, seeing that I am a poor man, of no great name?
24 And the servants of Saul gave him an account of what David had said.
25 And Saul said, Then say to David, The king has no desire for any bride-price, but only for the private parts of a hundred Philistines so that the king may get the better of his haters. But it was in Saul's mind that David might come to his end by the hands of the Philistines.
26 And when his servants said these words to David, he was well pleased to be the son-in-law of the king. And the days were still not past.
27 So David and his men got up and went, and put to death two hundred of the Philistines; and David took their private parts and gave the full number of them to the king, so that he might be the king's son-in-law. And Saul gave him his daughter Michal for his wife.
28 And it was clear to Saul that the Lord was with David; and he was loved by all Israel.
29 And Saul's fear of David became all the greater, and he went on hating him, day by day.