1 Samuel 17:17,18

Jesse said, Take now for thy brethren, &c. He thought provisions might be scarce with them. But, having other sons at home with him, it was, no doubt, through a divine influence that he sent David from the sheep upon this errand. Carry these ten cheeses unto the captain Whose favour might be very serviceable to them. And take their pledge That is, bring me some token of their welfare. Perhaps Jesse and his sons had fixed on some pledge between them, that they might be assured the messengers they sent to each other had been with them, and executed their commission.