Matthew Poole and continuators on 2 Samuel 23:16

16 And the three mighty men brake through the host of the Philistines , and drew water out of the well of Bethlehem, that was by the gate, and took it, and brought it to David: nevertheless he would not drink thereof x, but poured it out unto the LORD .

Which was in the Valley of Rephaim, v. 13. and in the way to Bethlehem. Lest by gratifying himself upon such terms, he should seem either to set too High a Price upon the satisfaction of his Appetite, or too low a Price upon the Lives of his Soldiers, or should encourage others to the like Vain-glorious and Foolish Attempts.

As a kind of Drink-offering, and acknowledgment of Gods goodness in preserving the Lives of his Captains in so dangerous an Enterprize; and to shew, that he esteemed it as a Sacred thing, which considering all things, it was not fit for him to drink it.