See you how Ahab humbles himself before me? because he humbles himself before me, I will not bring the evil in his days: but in his son's days will I bring the evil upon his house.
Read Chapter 21
Ambrose of Milan
In this place the question comes up: how do we interpret what the Lord said to Elijah: “Have you seen how Ahab has been moved at my presence? I will not bring evils in his days, but in his sons’ days will I bring evils”—or how do we say that repentance avails before God? “Behold, the king was moved before the face of the Lord and went away weeping, and he tore his garments, and covered himself with haircloth and put on sackcloth from that day on which he killed Naboth the Jezrehite,” so that mercy moved God, and he changed his decree. Therefore either repentance did not avail and did not turn God to mercy or the prophecy is false, for Ahab was vanquished and killed. But consider that he had a wife, Jezebel, by whose will he was inflamed and who turned his heart and made him execrable by reason of his excessive sacrileges. Accordingly, she checked even this desire of repentance on his part. But the Lord cannot be considered changeable if he did not think that he ought to keep for the on...
Sake. Hebrew, "before me "publicly. (Haydock)
The threat of the prophet caused Achab to invest his son with the royal dignity, and Josaphat followed his example. (Salien, the year before Christ 916.)
But some call this in question. (Haydock)