2 Peter 2:15

They have left the straight path and gone astray. They have followed the path of Balaam, the son of Beor, who set his heart on dishonest gain,

Revelation 2:14

Yet I hold it somewhat against you that you have among you some adherents of the teaching of Balaam, who taught Balak to entrap the children of Israel into eating meat that had been sacrificed to idols, and into immoral practices.

Treasury of Scripture Knowledge

Summary

Behold, these caused the children of Israel, through the counsel of Balaam, to commit trespass against the LORD in the matter of Peor, and there was a plague among the congregation of the LORD.

Bible References

These caused

2 Peter 2:15
They have left the straight path and gone astray. They have followed the path of Balaam, the son of Beor, who set his heart on dishonest gain,
Revelation 2:14
Yet I hold it somewhat against you that you have among you some adherents of the teaching of Balaam, who taught Balak to entrap the children of Israel into eating meat that had been sacrificed to idols, and into immoral practices.