15 The Philistines had war again with Israel; and David went down, and his servants with him, and fought against the Philistines. David grew faint; 16 and Ishbibenob, who was of the sons of the giant, the weight of whose spear was three hundred shekels of brass in weight, he being girded with a new sword, thought to have slain David. 17 But Abishai the son of Zeruiah helped him, and struck the Philistine, and killed him. Then the men of David swore to him, saying, “You shall go no more out with us to battle, that you don’t quench the lamp of Israel.”
18 It came to pass after this, that there was again war with the Philistines at Gob: then Sibbecai the Hushathite killed Saph, who was of the sons of the giant.
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.