12 Now David was the son of that Ephrathite of Beth-lehem-judah, whose name was Jesse; and he had eight sons: and the man was an old man in the days of Saul, stricken [in years] among men. 13 And the three eldest sons of Jesse had gone after Saul to the battle: and the names of his three sons that went to the battle were Eliab the first-born, and next unto him Abinadab, and the third Shammah. 14 And David was the youngest; and the three eldest followed Saul. 15 Now David went to and fro from Saul to feed his father's sheep at Beth-lehem.
Matthew Henry's Commentary on 1 Samuel 17:12-15
Commentary on 1 Samuel 17:12-30
(Read 1 Samuel 17:12-30)
Jesse little thought of sending his son to the army at that critical juncture; but the wise God orders actions and affairs, so as to serve his designs. In times of general formality and lukewarmness, every degree of zeal which implies readiness to go further, or to venture more in the cause of God than others, will be blamed as pride and ambition, and by none more than by near relations, like Eliab, or negligent superiors. It was a trial of David's meekness, patience, and constancy. He had right and reason on his side, and did not render railing for railing; with a soft answer he turned away his brother's wrath. This conquest of his own passion was more honourable than that of Goliath. Those who undertake great and public services, must not think it strange if they are spoken ill of, and opposed by those from whom they expect support and assistance. They must humbly go on with their work, in the face not only of enemies' threats, but of friends' slights and suspicions.