12 Enter David. He was the son of Jesse the Ephrathite from Bethlehem in Judah. Jesse, the father of eight sons, was himself too old to join Saul's army. 13 Jesse's three older sons had followed Saul to war. The names of the three sons who had joined up with Saul were Eliab, the firstborn; next, Abinadab; and third, Shammah. 14 David was the youngest son. While his three oldest brothers went to war with Saul, David went back and forth from attending to Saul to tending his father's sheep in Bethlehem. 15
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.