5 David went out and was successful wherever Saul sent him; as a result, Saul set him over the army. And all the people, even the servants of Saul, approved.
6 As they were coming home, when David returned from killing the Philistine, the women came out of all the towns of Israel, singing and dancing, to meet King Saul, with tambourines, with songs of joy, and with musical instruments. 7 And the women sang to one another as they made merry, "Saul has killed his thousands, and David his ten thousands." 8 Saul was very angry, for this saying displeased him. He said, "They have ascribed to David ten thousands, and to me they have ascribed thousands; what more can he have but the kingdom?" 9 So Saul eyed David from that day on.
Matthew Henry's Commentary on 1 Samuel 18:5-9
Commentary on 1 Samuel 18:1-5
(Read 1 Samuel 18:1-5)
The friendship of David and Jonathan was the effect of Divine grace, which produces in true believers one heart and one soul, and causes them to love each other. This union of souls is from partaking in the Spirit of Christ. Where God unites hearts, carnal matters are too weak to separate them. Those who love Christ as their own souls, will be willing to join themselves to him in an everlasting covenant. It was certainly a great proof of the power of God's grace in David, that he was able to bear all this respect and honour, without being lifted up above measure.
Commentary on 1 Samuel 18:6-11
(Read 1 Samuel 18:6-11)
David's troubles not only immediately follow his triumphs, but arise from them; such is the vanity of that which seems greatest in this world. It is a sign that the Spirit of God is departed from men, if, like Saul, they are peevish, envious, suspicious, and ill-natured. Compare David, with his harp in his hand, aiming to serve Saul, and Saul, with his javelin in his hand, aiming to slay David; and observe the sweetness and usefulness of God's persecuted people, and the barbarity of their persecutors. But David's safety must be ascribed to God's providence.