1 Samuel 17:20

And David rose up early in the morning, and left the sheep with a keeper, faithful to his charge also in this, and took, and went as Jesse had commanded him; and be came to the trench, the wagon rampart which served for a fortification of the camp, as the host was going forth to the fight, to be set up in battle array, and shouted for the battle, raised their war-cry, to encourage their own ranks and to terrify the enemies in case they should contemplate an attack.

And Jesse took an ass laden with bread, and a bottle, a skin, of wine, and a kid, as presents to the king, and sent them by David, his son, unto Saul, presents of this kind being a sign of obedience and subjection.