Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[310] After this came certain of the Ziphites, and told Saul that David was come again into their country, and if he would afford them his assistance, they could catch him. So he came to them with three thousand armed men; and upon the approach of night, he pitched his camp at a certain place called Hachilah. But when David heard that Saul was coming against him, he sent spies, and bid them let him know to what place of the country Saul was already come; and when they told him that he was at Hachilah, he concealed his going away from his companions, and came to Saul's camp, having taken with him Abishai, his sister Zeruiah's son, and Ahimelech the Hittite. Now Saul was asleep, and the armed men, with Abner their commander, lay round about him in a circle. Hereupon David entered into the king's tent; but he did neither kill Saul, though he knew where he lay, by the spear that was stuck down by him, nor did he give leave to Abishai, who would have killed him, and was earnestly bent upon it so to do; for he said it was a horrid crime to kill one that was ordained king by God, although he was a wicked man; for that he who gave him the dominion would in time inflict punishment upon him. So he restrained his eagerness; but that it might appear to have been in his power to have killed him when he refrained from it, he took his spear, and the cruse of water which stood by Saul as he lay asleep, without being perceived by any in the camp, who were all asleep, and went securely away, having performed every thing among the king's attendants that the opportunity afforded, and his boldness encouraged him to do. So when he had passed over a brook, and was gotten up to the top of a hill, whence he might be sufficiently heard, he cried aloud to Saul's soldiers, and to Abner their commander, and awaked them out of their sleep, and called both to him and to the people. Hereupon the commander heard him, and asked who it was that called him. To whom David replied, "It is I, the son of Jesse, whom you make a vagabond. But what is the matter? Dost thou, that art a man of so great dignity, and of the first rank in the king's court, take so little care of thy master's body? and is sleep of more consequence to thee than his preservation, and thy care of him? This negligence of yours deserves death, and punishment to be inflicted on you, who never perceived when, a little while ago, some of us entered into your camp, nay, as far as to the king himself, and to all the rest of you. If thou look for the king's spear and his cruse of water, thou wilt learn what a mighty misfortune was ready to overtake you in your very camp without your knowing it." Now when Saul knew David's voice, and understood that when he had him in his power while he was asleep, and his guards took no care of him, yet did not he kill him, but spared him, when he might justly have cut him off, he said that he owed him thanks for his preservation; and exhorted him to be of good courage, and not be afraid of suffering any mischief from him any more, and to return to his own home, for he was now persuaded that he did not love himself so well as he was loved by him: that he had driven away him that could guard him, and had given many demonstrations of his good-will to him: that he had forced him to live so long in a state of banishment, and in great fears of his life, destitute of his friends and his kindred, while still he was often saved by him, and frequently received his life again when it was evidently in danger of perishing. So David bade them send for the spear and the cruse of water, and take them back; adding this withal, That God would be the judge of both their dispositions, and of the actions that flowed from the same, "who knows that then it was this day in my power to have killed thee I abstained from it."