Ahab had seventy sons still living in Samaria. Jehu wrote letters addressed to the officers of Jezreel, the city elders, and those in charge of Ahab's sons, and posted them to Samaria.
The letters read:
Pick the best and most capable of your master's sons and put him on the throne. Prepare to fight for your master's position.
They were absolutely terrified at the letter. They said, "Two kings have already been wiped out by him; what hope do we have?"
So they sent the warden of the palace, the mayor of the city, the elders, and the guardians to Jehu with this message: "We are your servants. Whatever you say, we'll do. We're not making anyone king here. You're in charge - do what you think best."
Then Jehu wrote a second letter: If you are on my side and are willing to follow my orders, here's what you do: Decapitate the sons of your master and bring the heads to me by this time tomorrow in Jezreel.
When they got the letter, they took the king's sons and killed all seventy. Then they put the heads in baskets and sent them to Jehu in Jezreel.
A messenger reported to Jehu: "They've delivered the heads of the king's sons." He said, "Stack them in two piles at the city gate until morning."
In the morning Jehu came out, stood before the people, and addressed them formally: "Do you realize that this very day you are participants in God's righteous workings? True, I am the one who conspired against my master and assassinated him. But who, do you suppose, is responsible for this pile of skulls?
Know this for certain: Not a single syllable that God spoke in judgment on the family of Ahab is canceled; you're seeing it with your own eyes - God doing what, through Elijah, he said he'd do."
Then Jehu proceeded to kill everyone who had anything to do with Ahab's family in Jezreel - leaders, friends, priests. He wiped out the entire lot.
That done, he brushed himself off and set out for Samaria. Along the way, at Beth Eked (Binding House) of the Shepherds,
he met up with some relatives of Ahaziah king of Judah. Jehu said, "Who are you?" They said, "We're relatives of Ahaziah and we've come down to a reunion of the royal family."
"Grab them!" ordered Jehu. They were taken and then massacred at the well of Beth Eked. Forty-two of them - no survivors.
He went on from there and came upon Jehonadab the Recabite who was on his way to meet him. Greeting him, he said, "Are we together and of one mind in this?" Jehonadab said, "We are - count on me." "Then give me your hand," said Jehu. They shook hands on it and Jehonadab stepped up into the chariot with Jehu.
"Come along with me," said Jehu, "and witness my zeal for God." Together they proceeded in the chariot.
When they arrived in Samaria, Jehu massacred everyone left in Samaria who was in any way connected with Ahab - a mass execution, just as God had told Elijah.