Deuteronomy 13:12

8 you must not yield to him or listen to him. Show him no pity, and do not spare him or shield him.

9 Instead, you must surely kill him. Your hand must be the first against him to put him to death, and then the hands of all the people.

10 Stone him to death for trying to turn you away from the LORD your God, who brought you out of the land of Egypt, out of the house of slavery.

11 Then all Israel will hear and be afraid, and will never again do such a wicked thing among you.

12 If, regarding one of the cities the LORD your God is giving you to inhabit, you hear it said

13 that wicked men have arisen from among you and have led the people of their city astray, saying, “Let us go and serve other gods” (which you have not known),

14 then you must inquire, investigate, and interrogate thoroughly. And if it is established with certainty that this abomination has been committed among you,

15 you must surely put the inhabitants of that city to the sword. Devote to destruction all its people and livestock.

16 And you are to gather all its plunder in the middle of the public square, and completely burn the city and all its plunder as a whole burnt offering to the LORD your God. The city must remain a mound of ruins forever, never to be rebuilt.

Read all of Deuteronomy 13