Ahimelech the Hittite may have been a foreign mercenary (cf. Uriah the Hittite, 2 Sam. 11:3). The writer may have mentioned him to show the extent of David's appeal. Abishai was David's nephew, one of the sons of his sister Zeruiah (cf. 1 Chron. 2:15-16). Joab, who later became David's commander-in-chief, was Abishai's brother.
Saul had used his spear to attack David three times (cf. 18:10; 19:9-10; 20:33). It was, therefore, an instrument of death. It was also the symbol of Saul's rule similar to a scepter (cf. 22:6). Abishai's viewpoint was carnal. He concluded that because God had given David the upper hand he should use it to do away with his rival (v. 8; cf. 24:4). David had used similar words when he promised to kill Goliath (cf. 17:46) as had Saul in describing how he would kill David with his spear (cf. 18:11).
David believed, however, that since God had anointed Saul it was not his place to do him harm (v. 9; cf. 24:6-7). His reply to Abishai begins (v. 9) and ends (v. 11) with the reason David would not permit Abishai to kill Saul: he was the Lord's anointed. In the middle of this reply David mentioned alternative ways by which God might terminate Saul's life (v. 10). He might die from some physical affliction as Nabal had (cf. 25:38), or of natural causes, or in battle (cf. ch. 31). David reminded Abishai that God could deal with Saul without their help.
David's reason for entering Saul's camp was not to kill him but to teach him a lesson. By taking Saul's spear David would teach the king that he had the power of death but chose to spare Saul's life rather than taking it. This symbolic act also communicated that the right to rule would be David's eventually. By taking his water jug, a life-giving vessel since life in the Judean wilderness depended on drinking water, David taught him that he had the power to take Saul's life. Perhaps the jug of water also symbolized that refreshment and blessing would also be David's portion from the Lord. It was really the Lord who defended David by making Saul and all of his men sleep soundly (v. 12).