Numbers 16:1-2

Now Korah the son of Izhar, son of Kohath, son of Levi, and Dathan and Abiram the sons of Eliab, and On the son of Peleth, sons of Reuben, took men. And they rose up before Moses, with a number of the people of Israel, 250 chiefs of the congregation, chosen from the assembly, well-known men.