2 Samuel 16:12
It may be that the LORD will look on mine affliction, and that the LORD will requite me good for his cursing this day. It may be that the LORD will look on mine affliction, and that the LORD will requite me good for his cursing this day.
David accepted Shimei's abuse and cursing as what the Lord had permitted, part of the punishment brought on by his own sin which had caused his trouble. That sin had given the Lord's enemies occasion to blaspheme. He bore the insult humbly without seeking revenge.
He trusted humbly that the Lord sees his affliction and in hope of mercy may lessen it, repaying him with good for the cursing that day and turning the curse into a blessing. That trust was rewarded when God defeated Ahithophel's counsel and preserved David's life. When Shimei later confessed, David spared him and forgave him.