Now therefore, don't let my blood fall to the earth away from the presence of Yahweh: for the king of Israel is come out to seek a flea, as when one does hunt a partridge in the mountains.
So David is sort of chiding Abner the chief general of Saul, saying, "Hey you know your job is to guard the king, and you aren't doing a good job. You ought to be put to death. Someone came in to destroy the king, and you were just sound asleep. Look where the king's spear is, and the cruse of water."