King James Version
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.English Standard Version
Behold, these, on Balaam's advice, caused the people of Israel to act treacherously against the LORD in the incident of Peor, and so the plague came among the congregation of the LORD.New International Version
"They were the ones who followed Balaam's advice and were the means of turning the Israelites away from the LORD in what happened at Peor, so that a plague struck the LORD's people.