1 Samuel 26:16
This thing is not good that thou hast done. As the Lord liveth, ye are worthy to die, because ye have not kept your master, the Lord’s anointed. And now see where the king’s spear is, and the cruse of water that was at his bolster.
Cross-reference
In 1 Samuel 26:9, David refuses to harm Saul because he is the LORD's anointed — the same reverence that drives his condemnation of Abner in 26:16.
1 Samuel 26:11 shows David's own restraint toward the LORD's anointed, underscoring the gravity of Abner's failure to protect him in 26:16.
1 Samuel 24:6 records David's refusal to strike Saul for being the LORD's anointed — the same principle he uses to rebuke Abner in 26:16.
In 1 Samuel 20:31, Saul declares David must die — contrasting with David here declaring Abner deserves death for failing to protect Saul.
In 2 Samuel 12:5, David himself declares another man deserves to die — ironic parallel to his judgment of Abner here.
Lamentations 4:20 mourns the capture of 'the LORD's anointed' — a tragic outcome contrasting the protective reverence shown in 26:16.
Psalm 79:11 prays for those 'doomed to die' (sons of death) — the same phrase David uses to condemn Abner's negligence.
Psalm 102:20 also mentions 'those doomed to die' (sons of death) — the same idiom David uses to declare Abner's guilt.