Jamieson, Fausset and Brown on Numbers 16:12-14

12-14. Moses sent to call Dathan and Abiram--in a separate interview, the ground of their mutiny being different; for while Korah murmured against the exclusive appropriation of the priesthood to Aaron and his family, they were opposed to the supremacy of Moses in civil power. They refused to obey the summons; and their refusal was grounded on the plausible pretext that their stay in the desert was prolonged for some secret and selfish purposes of the leader, who was conducting them like blind men wherever it suited him.