Then Jehu gathered all the people together, and said to them, "Ahab served Baal a little, Jehu will serve him much.
Now therefore, call to me all the prophets of Baal, all his servants, and all his priests. Let no one be missing, for I have a great sacrifice for Baal. Whoever is missing shall not live." But Jehu acted deceptively, with the intent of destroying the worshipers of Baal.
And Jehu said, "Proclaim a solemn assembly for Baal." So they proclaimed it.
Then Jehu sent throughout all Israel; and all the worshipers of Baal came, so that there was not a man left who did not come. So they came into the temple of Baal, and the temple of Baal was full from one end to the other.
References for 2 Kings 10:21
And he said to the one in charge of the wardrobe, "Bring out vestments for all the worshipers of Baal." So he brought out vestments for them.
Then Jehu and Jehonadab the son of Rechab went into the temple of Baal, and said to the worshipers of Baal, "Search and see that no servants of the Lord are here with you, but only the worshipers of Baal."
So they went in to offer sacrifices and burnt offerings. Now Jehu had appointed for himself eighty men on the outside, and had said, "If any of the men whom I have brought into your hands escapes, whoever lets him escape, it shall be his life for the life of the other."
Now it happened, as soon as he had made an end of offering the burnt offering, that Jehu said to the guard and to the captains, "Go in and kill them; let no one come out!" And they killed them with the edge of the sword; then the guards and the officers threw them out, and went into the inner room of the temple of Baal.
And they brought the sacred pillars out of the temple of Baal and burned them.
Then they broke down the sacred pillar of Baal, and tore down the temple of Baal and made it a refuse dump to this day.
Thus Jehu destroyed Baal from Israel.
However Jehu did not turn away from the sins of Jeroboam the son of Nebat, who had made Israel sin, that is, from the golden calves that were at Bethel and Dan.
And the Lord said to Jehu, "Because you have done well in doing what is right in My sight, and have done to the house of Ahab all that was in My heart, your sons shall sit on the throne of Israel to the fourth generation."
But Jehu took no heed to walk in the law of the Lord God of Israel with all his heart; for he did not depart from the sins of Jeroboam, who had made Israel sin.
In those days the Lord began to cut off parts of Israel; and Hazael conquered them in all the territory of Israel
from the Jordan eastward: all the land of Gilead--Gad, Reuben, and Manasseh--from Aroer, which is by the River Arnon, including Gilead and Bashan.
Now the rest of the acts of Jehu, all that he did, and all his might, are they not written in the book of the chronicles of the kings of Israel?
So Jehu rested with his fathers, and they buried him in Samaria. Then Jehoahaz his son reigned in his place.
And the period that Jehu reigned over Israel in Samaria was twenty-eight years.