But one of the young men told Abigail, Nabal's wife, saying, Behold, David sent messengers out of the wilderness to Greet our master; and he railed at them.
This passage reveals that David and his men indeed had guarded Nabal's flocks of sheep for a long while, giving them marvelous protection.  "We know of raids on two walled towns in this south country, one by the Philistines  (1 Samuel 23:1-5) and one by the Amalekites  (1 Samuel 30:1-2).  How much more, then, must the shepherds in the open country have been in constant danger from marauders, unless they had someone like David to be a wall of protection to them."[12]