The special consideration that held back the arm of David from killing Saul was that he was the Lord's anointed. He held the office of king by Divine appointment,--not merely as other kings may be regarded as holding it, but as God's lieutenant, called specially, and selected for the office. For David to remove him would be to interfere with the Divine prerogative. It would be so much the more inexcusable as God had many other ways of removing him, any one of which He might readily employ. "David said furthermore, As the Lord liveth, the Lord shall smite him; or his day shall come to die; or he shall descend into battle, and perish. The Lord forbid that I should stretch forth mine hand against the Lord's anointed."
Let us briefly follow the narrative on each of the two occasions.
First, when David saw Saul asleep at the entrance of the cave near Engedi, he crept towards him as he lay, and removed a loose piece of his garment. When Saul rose up and proceeded on his way, David boldly followed him, believing that after sparing the king's life he was safe from attack either from him or his people. His respectful salutation, drawing the king's attention, was followed by an act of profound obeisance. David then addressed Saul somewhat elaborately, his address being wholly directed to the point of disabusing the king's mind of the idea that he had any plot whatever against his life. His words were very respectful but at the same time bold. Taking advantage of the act of forbearance which had just occurred, he demanded of the king why he listened to men's words, saying, Behold, David seeketh thy hurt. He protested that for himself nothing would induce him to stretch forth his hand against the Lord's anointed. That very day, he had had the chance, but he had forborne. His people had urged him, but he would not comply. _There_ was the skirt of his garment which he had just cut off: it would have been as easy for him, when he did that, to plunge his sword into the heart of the king. Could there be a plainer proof that Saul was mistaken in supposing David to be actuated by murderous or other sinful feelings against him? And yet Saul hunted for his life to take it. Rising still higher, David appealed to the great Judge of all, and placed the quarrel in His hands. To vary the case, he quoted a proverb to the effect that only where there was wickedness in the heart could wickedness be found in the life. Then, with the easy play of a versatile mind, he put the case in a comical light: did it become the great king of Israel to bring his hosts after one so insignificant--"after a dead dog, after a flea"? Was ocean to be tossed into tempest "to waft a feather or to drown a straw"? Once more, and to sum up the whole case, he appealed solemnly to God, virtually invoking His blessing on whoever was innocent in this quarrel, and calling down His wrath and destruction on the party that was really guilty.
The effect on Saul was prompt and striking. He was touched in his tenderest feelings by the singular generosity of his opponent. He broke down thoroughly, welcomed the dear voice of David, "lifted up his voice and wept." He confessed that he was wrong, that David had rewarded him good and he had rewarded David evil. David had given him that day a convincing proof of his integrity; though it seemed that the Lord had delivered him into his hand, he killed him not. He had reversed the principle on which men were accustomed to act when they came upon an enemy, and had him in their power. And all these acknowledgments of David's superior goodness Saul made, while knowing well and frankly owning that David should be the king, and that the kingdom should be established in his hand. One favour only Saul would beg of David in reference to that coming time--that he would not massacre his family, or destroy his name out of his father's house--a request which it was easy for David to comply with. Never would he dream of such a thing, however common it was in these Eastern kingdoms. David sware to Saul, and the two parted in peace.