Numbers 25:1-5

And Israel abode in Shittim; and the people began to play the harlot with the daughters of Moab: for they called the people unto the sacrifices of their gods; and the people did eat, and bowed down to their gods. And Israel joined himself unto Baal-peor: and the anger of Jehovah was kindled against Israel. And Jehovah said unto Moses, Take all the chiefs of the people, and hang them up unto Jehovah before the sun, that the fierce anger of Jehovah may turn away from Israel. And Moses said unto the judges of Israel, Slay ye every one his men that have joined themselves unto Baal-peor.