1 Samuel 24:4
And the men of David said unto him, Behold the day of which the Lord said unto thee, Behold, I will deliver thine enemy into thine hand, that thou mayest do to him as it shall seem good unto thee. Then David arose, and cut off the skirt of Saul’s robe privily.
Cross-references
1 Samuel 24:10 is David's own speech recalling the event — he says 'some told me to kill you' referring to v.4.
In 1 Samuel 24:18, Saul acknowledges David spared him when God gave him into his hands — confirming the mercy shown in v.4.
In 1 Samuel 23:7, Saul thinks God gave David into his hand — here the tables are turned as God gives Saul into David's hand.
In 1 Samuel 26:8-11, Abishai urges David to kill Saul, and David again refuses to strike the Lord's anointed — a direct parallel to this scene.
In 1 Samuel 26:23, David repeats his refusal to harm the Lord's anointed — the same principle he acted on in 24:4.
In 1 Samuel 26:12, David again spares Saul by taking his spear — a parallel act of restraint toward God's anointed.
In 2 Samuel 4:8, men bring Ish-bosheth's head claiming God avenged — David rejects them, consistent with sparing Saul in the cave.