Poured it out unto the Lord - To make libations, both of water and wine, was a frequent custom among the heathens. We have an almost similar account in Arrian's Life of Alexander: "When his army was greatly oppressed with heat and thirst, a soldier brought him a cup of water; he ordered it to be carried back, saying, I cannot bear to drink alone while so many are in want, and this cup is too small to be divided among the whole." Tunc poculo pleno sicut oblatum est reddito: Non solus, inquit, bibere sustineo, nec tam exiguum dividere omnibus possum. - Arrian, lib. vi.
The example was noble in both cases, but David added piety to bravery; he poured it out unto the Lord.

And he said, be it far from me, O Lord, that one should do this,.... Drink of the water these men had brought him:

is not this the blood of the men that went in jeopardy of their lives? who risked the shedding of their blood, and went in danger of their lives to get it:

therefore he would not drink it: some compare with this the story of Alexander (d) to whom a vessel of water was offered when in extreme thirst, which he refused, because he could not bear to drink it alone, and so small a quantity could not be divided among all about him; but the reasons are not the same:

these things did these three mighty men; which made them very famous.

(d) Curt. Hist. l. 7. c. 5.