דברי הימים א, פרק י״א, פסוק י״ח

A profound bond of loyalty is revealed through the actions of David's three mighty warriors, who willingly risked their lives behind enemy lines. Hearing a wish from their leader, these men, driven by deep love and admiration, took personal initiative to bring him comfort [מצודת דוד, ביאור שטיינזלץ]. They actively fought their way through the fortified Philistine camp, carving a path as though tearing the entire camp in two [מצודת דוד, ביאור שטיינזלץ].

When they reached the well, they found the Philistines standing guard and blocking all access. Undeterred, the warriors broke through the defensive lines and drew the water by force, acting completely against the will of the enemy [רש״י].

They returned from this dangerous mission with the water. Yet, despite the immense effort and risk his men had just undertaken, David refused to drink it. Instead, he chose to pour the water out to God. The exact nature of this act is understood in different ways. One perspective suggests that David simply poured the water onto the ground as an act of devotion for the sake of God [מצודת דוד, ביאור שטיינזלץ]. Another tradition places this event specifically during the festival of Sukkot. According to this view, David used this water to fulfill the specific holiday commandment of pouring water directly upon the altar [רש״י].