Numbers 25:3-9

3And Israel joined himself to Baalpeor: and the anger of the LORD was kindled against Israel. 4And the LORD said to Moses, Take all the heads of the people, and hang them up before the LORD before the sun, that the fierce anger of the LORD may be turned away from Israel. 5And Moses said to the judges of Israel, Slay ye every one his men that were joined to Baalpeor.

6And, behold, one of the children of Israel came and brought to his brethren a Midianitish woman in the sight of Moses, and in the sight of all the congregation of the children of Israel, who were weeping before the door of the tabernacle of the congregation. 7And when Phinehas, the son of Eleazar, the son of Aaron the priest, saw it, he rose from among the congregation, and took a javelin in his hand; 8And he went after the man of Israel into the tent, and thrust both of them through, the man of Israel, and the woman through her belly. So the plague was stayed from the children of Israel. 9And those that died in the plague were twenty and four thousand.