Now then do it: for the LORD hath spoken of David, saying, By the hand of my servant David I will save my people Israel out of the hand of the Philistines, and out of the hand of all their enemies. The Lord hath spoken of David - Where is this spoken? Such a promise is not extant. Perhaps it means no more than, "Thus, it may be presumed, God hath determined."
Related Commentaries of 2 Samuel 3:18
2 Samuel 3:18
18 Now then do it: for the LORD hath spoken of David, saying, By the hand of my servant David I will save my people Israel out of the hand of the Philistines, and out of the hand of all their enemies.