Numbers 25:1, 6-8

While Israel was staying in the Acacia Grove,  , the people began to prostitute themselves with the women of Moab.

An Israelite man came bringing a Midianite woman to his relatives in the sight of Moses and the whole Israelite community while they were weeping at the entrance to the tent of meeting. When Phinehas son of Eleazar, son of Aaron the priest, saw this, he got up from the assembly, took a spear in his hand, followed the Israelite man into the tent,  and drove it through both the Israelite man and the woman — through her belly. Then the plague on the Israelites was stopped