17 And Saul said to David, Behold, my elder daughter Merab, her will I give thee to wife: only be thou valiant for me, and fight Jehovah's battles. For Saul said, Let not my hand be upon him, but let the hand of the Philistines be upon him. 18 And David said unto Saul, Who am I, and what is my life, [or] my father's family in Israel, that I should be son-in-law to the king? 19 But it came to pass at the time when Merab, Saul's daughter, should have been given to David, that she was given unto Adriel the Meholathite to wife. 20 And Michal, Saul's daughter, loved David: and they told Saul, and the thing pleased him. 21 And Saul said, I will give him her, that she may be a snare to him, and that the hand of the Philistines may be against him. Wherefore Saul said to David, Thou shalt this day be my son-in-law a second time.
Matthew Henry's Commentary on 1 Samuel 18:17-21
Commentary on 1 Samuel 18:12-30
(Read 1 Samuel 18:12-30)
For a long time David was kept in continual apprehension of falling by the hand of Saul, yet he persevered in meek and respectful behaviour towards his persecutor. How uncommon is such prudence and discretion, especially under insults and provocations! Let us inquire if we imitate this part of the exemplary character before us. Are we behaving wisely in all our ways? Is there no sinful omission, no rashness of spirit, nothing wrong in our conduct? Opposition and perverseness in others, will not excuse wrong tempers in us, but should increase our care, and attention to the duties of our station. Consider Him that endured contradiction of sinners against himself, lest ye be weary and faint in your minds, Hebrews 12:3. If David magnified the honour of being son-in-law to king Saul, how should we magnify the honour of being sons to the King of kings!