In 1 Chronicles 11:15-19, we read the account of David sending three of his men to get him water from the well at Bethlehem. But once he receives it, David pours it out on the ground. Matthew Henry explains why:
"[This was] repentance for [David's] own weakness. It is really an honor to a man, when he is made sensible that he has said or done any thing unadvisedly, to unsay it and undo it again by repentance, as it is a shame to a man when he has said or done amiss to stand to it. [This was also] denial of [David's] own appetite. He longed for the water of the well of Bethlehem; but, when he had it, he would not drink it, because he would not so far humor himself and gratify a foolish fancy. He that has such a rule as this over his own spirit is better than the mighty. It is an honor to a man to have the command of himself; but he that will command himself must sometimes cross himself."