Charles Ellicott Commentary 1 Samuel 16:20

"And Jesse took an ass [laden] with bread, and a bottle of wine, and a kid, and sent them by David his son unto Saul." — 1 Samuel 16:20 (ASV)

And Jesse took an ass. —It was and is still customary in the East to acknowledge obedience and subjection with a present. Jesse, the sheik of Bethlehem, would thus be expected on sending his son to the court of Saul to acknowledge his sovereign by some token of homage.

The nature of Jesse’s gifts shows how simple and primitive were the customs of the Hebrew people at that time.