Bamidbar 16:1-2

Now Korach ben Yitzhar ben Kehat ben Levi, and Datan and Aviram, the Bnei Eliav, and On ben Pelet, Bnei Reuven, became insolent; And they rose up before Moshe, with certain of the Bnei Yisroel, two hundred and fifty Nasi'ei Edah, chosen from the assembly, men of renown