Saul had not hitherto fulfilled the promise of which David had heard (marginal reference); nor was it unnatural that Saul should delay to do so, until the shepherd's boy had risen to a higher rank.

Fight the Lord's battles - Mr. Calmet properly remarks that the wars of the Hebrews, while conducted by the express orders of God, were truly the wars of the Lord; but when the spirit of worldly ambition and domination became mingled with them, they were no longer the wars of the Lord, but wars of lust and profanity.

And Saul said to David,.... Not in friendship and good will to him, but designing to lay a snare for him:

behold, my eldest daughter Merab, her will I give thee to wife; most interpreters understand it, that he was obliged to this by promise, on account of David's slaying Goliath, 1 Samuel 17:25; but Abarbinel is of another mind, and he rightly observes, that the words referred to are not the words of Saul, but of the men of Israel, who might suppose what the king would do; or if they heard anything like it spoken by Saul, it was only in a hyperbolical way, signifying he did not care what he gave, and what he parted with, to the man that killed the Philistine, but was not strictly bound to this particular thereby; nor did David ever claim such promise, nor did Saul think himself bound to do it, but proposes it as an instance of his great kindness and favour, as he pretended, and therefore expected great returns for it, as follows:

only be thou valiant for me, and fight the Lord's battles: he knew he was a valiant man, and ready enough to fight; but he expected that in consideration of such a favour, and such high honour as this, that he would exert himself in an extraordinary manner, and engage in hazardous attempts, and show himself worthy to be the son of a king, in the defence of him and of his country, and for the glory of the God of Israel; all this he suggests, when his view was, that he should expose his life to such danger, that it might be hoped it would be taken away:

for Saul said; not openly and verbally, but in his heart; he thought within himself:

let not mine hand be upon him; he had attempted to lay hands on him, or to kill him with his own hands, but now he thought better, and consulted his credit among the people:

but let the hand of the Philistines be upon him; he hoped by these means that he would fall by their hands at the head of his troop, while he was displaying his valour, and hazarding his life for the good of his king and country; what Saul contrived proved his own case, he died in battle with the Philistines, 1 Samuel 31:4.

Craftiness of Saul in the betrothal of his daughters to David. - 1 Samuel 18:17. As Saul had promised to give his daughter for a wife to the conqueror of Goliath (1 Samuel 17:25), he felt obliged, by the growing love and attachment of the people to David, to fulfil this promise, and told him that he was ready to do so, with the hope of finding in this some means of destroying David. He therefore offered him his elder daughter Merab with words that sounded friendly and kind: "Only be a brave man to me, and wage the wars of the Lord." He called the wars with the Philistines "wars of Jehovah," i.e., wars for the maintenance and defence of the kingdom of God, to conceal his own cunning design, and make David feel all the more sure that the king's heart was only set upon the welfare of the kingdom of God. Whoever waged the wars of the Lord might also hope for the help of the Lord. But Saul had intentions of a very different kind. He thought ("said," sc., to himself), "My hand shall not be upon him, but let the hand of the Philistines be upon him;" i.e., I will not put him to death; the Philistines may do that. When Saul's reason had returned, he shrank from laying hands upon David again, as he had done before in a fit of madness. He therefore hoped to destroy him through the medium of the Philistines.

And Saul said to David, Behold my elder daughter Merab, her will I give thee to wife: only be thou valiant for me, and {g} fight the LORD'S battles. For Saul said, Let not mine hand be upon him, but let the hand of the Philistines be upon him.

(g) Fight against them that war against God's people.

valiant: Heb. a son of valour

1Sa 18:17-21. He Offers Him His Daughter for a Snare.

17. Saul said to David, Behold my elder daughter Merab, her will I give thee to wife-Though bound to this already [1Sa 17:25], he had found it convenient to forget his former promise. He now holds it out as a new offer, which would tempt David to give additional proofs of his valor. But the fickle and perfidious monarch broke his pledge at the time when the marriage was on the eve of being celebrated, and bestowed Merab on another man (see on [246]2Sa 21:8); an indignity as well as a wrong, which was calculated deeply to wound the feelings and provoke the resentment of David. Perhaps it was intended to do so, that advantage might be taken of his indiscretion. But David was preserved from this snare.

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, Heb 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!