Numbers 16:1-2

Korah (son of Izhar), Dathan and Abiram (sons of Eliab), and On (son of Peleth) dared to challenge Moses. (Korah was a descendant of Kohath and Levi. Dathan, Abiram, and On were descendants of Reuben.) These four men were joined by 250 Israelite men, well-known leaders of the community, chosen by the assembly.