25 Surely there was no one like Ahab who sold himself to do evil in the sight of the Lord, because Jezebel his wife incited him. 26 He acted very abominably in following idols, according to all that the Amorites had done, whom the Lord cast out before the sons of Israel.

27 It came about when Ahab heard these words, that he tore his clothes and put on sackcloth and fasted, and he lay in sackcloth and went about despondently. 28 Then the word of the Lord came to Elijah the Tishbite, saying, 29 “Do you see how Ahab has humbled himself before Me? Because he has humbled himself before Me, I will not bring the evil in his days, but I will bring the evil upon his house in his son’s days.”

Source: https://bible.knowing-jesus.com/readings/Ahab~s-Repentance

What Made King Ahab the Evilest King of Israel?
The People Israel became the People Israel when Yahweh (their sovereign God) gave the Ten Commandments to Moses on Mount Sinai. Which of the Ten Commandments (literally in Hebrew, “The Ten Utterances”) are most absolutely required? Answer: you must believe Number One and act on Number Two. Number one is “I am the Lord your God who has taken you out of the land of Egypt.” Number Two is “You shall have no other gods but me.”

That’s where King Ahab fell. Though he was the seventh king of Israel and ought to have known better, King Ahab took up another god than Yahweh, worshipping that god as equal to or greater than Yahweh.

Why Would King Ahab do That?
King Ahab had two problems. One, he could be manipulated. Two, he had a forceful wife. He was married to none other than Jezebel.

Jezebel was the daughter of Ethbaal, king of the Sidonians. Ethbaal became king by murdering his predecessor at Tyre, thus providing him the kingship of all the Phoenician cities. The royal marriage between Ahab and Jezebel may have benefitted Ahab by binding Israel with Tyre. It also may have occurred at just the right time for King Ahab—when Aramean powers of Syria were threatening Israel’s coastal cities.

So, modern readers may consider King Ahab’s marriage a political triumph. But is that so? Were all of Jezebel’s gifts to her husband and urgencies to manipulate his behavior equally beneficial?

Nowadays, Jezebel is often condemned. Who would want her as a wife? Her seductive ways, excessive personal beautification, manipulation of others even to the extent of having them killed, and excitement to acquire whatever power she could. These may be accurate historical characterizations. Jezebel was, after all, a woman who seethed to be Queen and was the daughter of a murderous father (a father whose family history illustrated at least one way to become ruler). However, from the biblical point of view, Jezebel’s most appalling sin was worse than murder. It was idolatry.

The People Israel may have been affronted by Jezebel’s sexual, political, and criminal behavior. Among other things, she engineered the murder of Naboth, whose orchard King Ahab wanted for his garden and could not get legally. So, Jezebel got the orchard for her husband any way by having the man Naboth killed (1 Kings 21:1-16). That was bad. But what may have been even worse was Jezebel’s theological cluelessness or, even worse, her rebelliousness.