Charles Ellicott Commentary Numbers 16:5

"and he spake unto Korah and unto all his company, saying, In the morning Jehovah will show who are his, and who is holy, and will cause him to come near unto him: even him whom he shall choose will he cause to come near unto him." — Numbers 16:5 (ASV)

And he spake unto Korah and unto all his company—The words seem to have been addressed only to Korah and his company, not to Dathan and Abiram, who do not appear to have been present on this occasion. (See Numbers 16:12, where Moses is represented as sending for Dathan and Abiram.)

Even to-morrow—Literally, In the morning. It may be that On and also the sons of Korah profited by this suspension of the judgment which was about to overtake those who persisted in their rebellion.