Saul said to David, "Here is my older daughter Merab. I will give her to you in marriage; only serve me bravely and fight the battles of the LORD." For Saul said to himself, "I will not raise a hand against him. Let the Philistines do that!"
But David said to Saul, "Who am I, and what is my family or my father's clan in Israel, that I should become the king's son-in-law?" So when the time came for Merab, Saul's daughter, to be given to David, she was given in marriage to Adriel of Meholah.
When the attendants told David these things, he was pleased to become the king's son-in-law. So before the allotted time elapsed, David and his men went out and killed two hundred Philistines. He brought their foreskins and presented the full number to the king so that he might become the king's son-in-law. Then Saul gave him his daughter Michal in marriage.
When Saul realized that the LORD was with David and that his daughter Michal loved David, Saul became still more afraid of him, and he remained his enemy the rest of his days.
The Philistine commanders continued to go out to battle, and as often as they did, David met with more success than the rest of Saul's officers, and his name became well known. 1 Samuel 18: 17-19, 26-30
Again we see the love/hate relationship that Saul has with David. He hates him and wants to kill him; then suggests that his daughter marry him! How would you like to have King Saul as your father-in-law? Holiday dinners would be interesting to say the least!
Finally, though, David married Michal, but was still a commander in Saul's army. Scripture also says that David met with more success than the rest of Saul's officers. Showing up your fellow officers time and time again isn't a way to endear yourself towards them. But David knew the Lord was with him. More importantly, Saul knew that the Lord was with David (he still tried to kill him on occasion, but he knew that the Lord had watched over David).
Saul recognized that the Spirit of the Lord was on David. Pray, too, that the Spirit of the Lord will also guide our politicians and leaders. Pray that those who are vocal about their faith will continue to do so.