1 Samuel 25:31
That this shall be no grief unto thee, nor offence of heart unto my lord, either that thou hast shed blood causeless, or that my lord hath avenged himself: but when the LORD shall have dealt well with my lord, then remember thine handmaid.
This belongs to the time when David was still hunted by Saul, after Abiathar the son of Ahimelech escaped to David following Saul's slaughter of the Lord's priests and David took him into safeguard and protection. It is part of Abigail's humble appeal to David, whose piety was shown in her words and actions during their encounter. In it Abigail warns David that shedding blood without cause by killing Nabal and his household to avenge himself would afterward become a grief to him and a trouble to his conscience with guilt.
That guilt would weigh especially when the Lord fulfilled His promises to David, prospered him, and appointed him ruler over Israel, leaving him to regret what he had done. David was to fight the Lord's battles rather than avenge his own personal wrongs. He had intended to take revenge on Nabal and his household, but Abigail's appeal and intervention turned him away from that evil act of vengeance.
Abigail asks David to remember her when the Lord has dealt well with him, prospered him, and made him ruler over Israel. David promised to remember her request when he ruled over Israel and not to retaliate for Nabal's insult.