10 Jesse had seven of his sons pass before Samuel, but Samuel said to him, "The Lord has not chosen these."
12 Now David was the son of an Ephrathite named Jesse, who was from Bethlehem in Judah. Jesse had eight sons, and in Saul's time he was very old.
(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.
Matthew Henry's Commentary on 1 Samuel 16:10
Commentary on 1 Samuel 16:6-13
(Read 1 Samuel 16:6-13)
It was strange that Samuel, who had been so disappointed in Saul, whose countenance and stature recommended him, should judge of another man by that rule. We can tell how men look, but God can tell what they are. He judges of men by the heart. We often form a mistaken judgment of characters; but the Lord values only the faith, fear, and love, which are planted in the heart, beyond human discernment. And God does not favour our children according to our fond partiality, but often most honours and blesses those who have been least regarded. David at length was pitched upon. He was the youngest of the sons of Jesse; his name signifies Beloved; he was a type of God's beloved Son. It should seem, David was least set by of all the sons of Jesse. But the Spirit of the Lord came upon David from that day forward. His anointing was not an empty ceremony, a Divine power went with that instituted sign; he found himself advanced in wisdom and courage, with all the qualifications of a prince, though not advanced in his outward circumstances. This would satisfy him that his election was of God. The best evidence of our being predestinated to the kingdom of glory, is, our being sealed with the Spirit of promise, and experience of a work of grace in our hearts.