1 Chronicles 11:18
And the three brake through the host of the Philistines, and drew water out of the well of Beth-lehem, that was by the gate, and took it, and brought it to David: but David would not drink of it, but poured it out to the LORD, And the three brake through the host of the Philistines, and drew water out of the well of Beth-lehem, that was by the gate, and took it, and brought it to David: but David would not drink of it, but poured it out to the LORD,
The three obtained the water at the risk of their own lives by breaking through the host of the Philistines to the well at Bethlehem. Because it had been gained at such cost, David regarded it as too sacred for ordinary drinking. To drink it would have been like drinking the blood of the men who had imperiled themselves to bring it. He therefore poured it out to the Lord as an offering to God, honoring their lives and treating what they had brought as a sacred gift.