Elijah had warned Ahab that he and his descendants would pay for their idolatry, their murder of God’s prophets, and their wicked influence (I Kings 21:17-29). Ahab had repented at that time, and God had postponed the judgment until after Ahab’s death. But now the bill had come due; God’s judgment was about to fall on Ahab’s house through both Hazael the king of Syria and Jehu the king of Israel.
Note vs. 7: 2Ki 9:7 And thou shalt smite the house of Ahab thy master, that I may avenge the blood of my servants the prophets, and the blood of all the servants of the LORD, at the hand of Jezebel.
Notice the word “avenge.” The Bible often refers to God’s vengeance.
Cf. Deuteronomy 32:35 Vengeance is Mine, and recompense;
Deuteronomy 32:43 …[God] will avenge the blood of His servants, And render vengeance to His adversaries…
Luke 18:7 And shall God not avenge His own elect who cry out day and night to Him, though He bears long with them?
Romans 12:19 … it is written, “Vengeance is Mine, I will repay,” says the Lord. (quoting Deut 32:35)
1 Thessalonians 4:6 … the Lord is the avenger …
Revelation 6:10 And they cried with a loud voice, saying, “How long, O Lord, holy and true, until You judge and avenge our blood on those who dwell on the earth?”
What is vengeance? It is retaliation for an evil deed; punishment given for one’s sinful behavior. God promises to repay people for the evil that they’ve done. We are not to take vengeance or seek revenge. We are to leave that to God; that’s his business. He’s the righteous judge, and he will make sure that the guilty will reap what they’ve sown. People will get what they deserve.
Isa 3:11 Woe to the wicked! It shall be ill with him, For the reward of his hands shall be given him.
Quote: When men and women violate God’s laws, when they ignore his calls to repent and when they abuse his servants, God is committed to avenge such activity with his own judgements.
Many people today dismiss the idea of God’s vengeance. They like to think about God as loving, kind, tolerant, and benevolent, not judgmental. God to them is like a heavenly grandfather who ignores the bad behavior of his grandkids. But because God is holy, he must also judge righteously. The judge of all the earth will do right, and that requires him to mete out righteous judgment.
We certainly don’t deny that God is loving, kind, and compassionate. God provides a way of escaping retribution for our sins—he provided a sacrifice who took that judgment for us—Jesus. If we repent of sin and believe the Gospel, we avoid experiencing God’s vengeance. But if you don’t, you won’t.
In our passage today, we see several ways that God causes vengeance to fall on unrepentant sinners. If you fail to repent and believe the Gospel, you could experience these same kinds of expressions of God’s vengeance.
 John Cheeseman, Elisha: Man of Mission, Man of Miracles, People in the Bible (Leominster: Day One, 2015), 87.