Jamieson, Fausset and Brown on 1 Samuel 25:4-9

4-9. Nabal did shear his sheep, and David sent out ten young men, &c.--David and his men lurked in these deserts, associating with the herdsmen and shepherds of Nabal and others and doing them good offices, probably in return for information and supplies obtained through them. Hence when Nabal held his annual sheep-shearing in Carmel, David felt himself entitled to share in the festival and sent a message, recounting his own services and asking for a present. "In all these particulars we were deeply struck with the truth and strength of the biblical description of manners and customs almost identically the same as they exist at the present day. On such a festive occasion, near a town or village, even in our own time, an Arab sheik of the neighboring desert would hardly fail to put in a word either in person or by message; and his message, both in form and substance, would be only a transcript of that of David" [Robinson].

1Sa 25:10-13. The Churlish Answer Provokes Him.