15 The Philistines went to war again with Israel, and David went down together with his servants. They fought against the Philistines, and David grew weary. 16 Ishbi-benob, one of the descendants of the giants, whose spear weighed three hundred shekels of bronze, and who was fitted out with new weapons, said he would kill David. 17 But Abishai son of Zeruiah came to his aid, and attacked the Philistine and killed him. Then David's men swore to him, "You shall not go out with us to battle any longer, so that you do not quench the lamp of Israel."
18 After this a battle took place with the Philistines, at Gob; then Sibbecai the Hushathite killed Saph, who was one of the descendants of the giants.
Matthew Henry's Commentary on 2 Samuel 21:15-18
Commentary on 2 Samuel 21:15-22
(Read 2 Samuel 21:15-22)
These events seem to have taken place towards the end of David's reign. David fainted, but he did not flee, and God sent help in the time of need. In spiritual conflicts, even strong saints sometimes wax faint; then Satan attacks them furiously; but those who stand their ground and resist him, shall be relieved and made more than conquerors. Death is a Christian's last enemy, and a son of Anak; but through Him that triumphed for us, believers shall be more than conquerors at last, even over that enemy.