(NIV1984) 1 Kings 21:29b – “‘Because he has humbled himself, I will not bring this disaster in his day, but I will bring it on his house in the days of his son.'”
And thus God is merciful to Ahab. Ahab’s humility at the prophecy against him caused God to put off the days of his family’s destruction. This is a reward for Ahab’s humility.
This is, again, an encouragement. God noticed the humility of a man like Ahab. If Ahab was able to be humble, why would we not be able to?