Then answered David and said to Ahimelech the Hittite, and to Abishai the son of Zeruiah, brother to Joab, saying, Who will go down with me to Saul to the camp? Abishai said, I will go down with you.
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."