In Numbers 25, the Israelites are punished for their idolatry and immorality. The Lord commands Moses to take vengeance on the Midianites, who had enticed the Israelites to worship their gods. Moses then sends a thousand men from each tribe to fight against the Midianites. The Israelites are victorious and bring back the spoils of war.
The chapter then turns to the story of Phinehas, the son of Eleazar. Phinehas had seen an Israelite man and a Midianite woman together and had taken action to stop their immoral behavior. He had killed them both, thus preventing the spread of idolatry among the Israelites. The Lord rewards Phinehas for his zeal and grants him and his descendants a covenant of peace.
The chapter ends with a reminder to the Israelites to remain faithful to the Lord and to avoid idolatry. This is a reminder to us today that we should remain faithful to God and avoid any behavior that would lead us away from Him.