15 And David said longingly, "Oh, that someone would give me water to drink from the well of Bethlehem that is by the gate!" 16 Then the three mighty men broke through the camp of the Philistines and drew water out of the well of Bethlehem that was by the gate and carried and brought it to David. But he would not drink of it. He poured it out to the Lord 17 and said, "Far be it from me, O Lord, that I should do this. Shall I drink the blood of the men who went at the risk of their lives?" Therefore he would not drink it. These things the three mighty men did.
Matthew Henry's Commentary on 2 Samuel 23:15-17
Commentary on 2 Samuel 23:8-39
(Read 2 Samuel 23:8-39)
David once earnestly longed for the water at the well of Bethlehem. It seems to be an instance of weakness. He was thirsty; with the water of that well he had often refreshed himself when a youth, and it was without due thought that he desired it. Were his valiant men so forward to expose themselves, upon the least hint of their prince's mind, and so eager to please him, and shall not we long to approve ourselves to our Lord Jesus, by ready compliance with his will, as shown us by his word, Spirit, and providence? But David poured out the water as a drink-offering to the Lord. Thus he would cross his own foolish fancy, and punish himself for indulging it, and show that he had sober thoughts to correct his rash ones, and knew how to deny himself. Did David look upon that water as very precious which was got at the hazard of these men's blood, and shall not we much more value those benefits for purchasing which our blessed Saviour shed his blood? Let all beware of neglecting so great salvation.