Numbers 25:16-18

16Then the Lord spoke to Moses, saying,

17“1Be hostile to the Midianites and strike them;

18for they have been hostile to you with their tricks, with which they have deceived you in the affair of Peor and in the affair of Cozbi, the daughter of the leader of Midian, their sister who was slain on the day of the plague because of Peor.”