Or HaChaim on Numbers 16:26/אור החיים על במדבר ט״ז:כ״ו

1 וידבר אל העדה לאמור, He spoke to the congregation, saying, etc. The word לאמור means here that Moses told the people that he had been instructed by G'd to tell them what he was about to say.

2סורו נא מעל אהלי האנשים הרשעים האלה, "please depart from the tents of these wicked men." Moses was very astute in requesting from the people that by their departure from the tents of Korach they should indicate that they considered these men as wicked and about to perish. They should be afraid lest the evil that would overtake these men would also overtake them. If that would be the motivation behind their removing their presence from the tents of Korach G'd would interpret this positively and save them also from coming to harm. Even though G'd had already indicated that it was sufficient to merely remove oneself from Korach's tent, the righteous, such as Moses, are always concerned with helping their contemporaries to acquire additional merits.