The Sin at Baal-peor

Numbers 25:1-5

And Israel at that time abode in Settim, and the people committed fornication with the daughters of Moab,

Who called them to their sacrifices. And they ate of them, and adored their gods.

And Israel was initiated to Beelphegor: upon which the Lord being angry,

Said to Moses: Take all the princes of the people, and hang them up on gibbets against the sun: that my fury may be turned away from Israel.

And Moses said to the judges of Israel: Let every man kill his neighbours, that have been initiated to Beelphegor.