Numbers 23-25

This Balak-Balaam story if kinda strange and quite comical. After the talking donkey incident, the exchange is between Balak and Balaam, and is quite amusing as Balak tries to get Balaam to curse Israel, but instead Balaam obeys YHWH and blesses Israel. Finally though, instead of curses, Balaam provides a prophesy of destruction of Moab.
¹⁵Then he uttered his oracle: "The oracle of Balaam son of Beor, the oracle of one whose eye sees clearly, ¹⁶the oracle of one who hears the words of God, who has knowledge from the Most High, who sees a vision from the Almighty, who falls prostrate, and whose eyes are opened: ¹⁷"I see him, but not now; I behold him, but not near. A star will come out of Jacob; a scepter will rise out of Israel. He will crush the foreheads of Moab, the skulls of all the sons of Sheth. ¹⁸Edom will be conquered; Seir, his enemy, will be conquered, but Israel will grow strong. ¹⁹A ruler will come out of Jacob and destroy the survivors of the city."

While they were in Shittim, the Israelites began to fool around with the Moabite women and also participating in the worship of Baal, God of Peor. YHWH is furious and through Moses, pronounces a death sentence on these men. Eleazar, son of Aaron, publicly spears one of these me to death, and is commended by YHWH.

YHWH pronounces death sentence on all Midianites.
¹⁶The LORD said to Moses, ¹⁷"Treat the Midianites as enemies and kill them, ¹⁸because they treated you as enemies when they deceived you in the affair of Peor and their sister Cozbi, the daughter of a Midianite leader, the woman who was killed when the plague came as a result of Peor."

This must have caused some discomfort to Moses, who has a Midianite wife!!