Having already issued a warning to separate from the congregation (in Pasuk 21), why did Hashem see fit to warn them again?
Targum Yonasan: Before He warned Moshe and Aharon to leave the vicinity of all the people; now, having accepted Moshe's Tefilah, He was warning all the people to leave the vicinity of Korach and his congregation.
Seforno: Hashem clarified that the order was to leave the vicinity only of Korach's congregation.
Oznayim la'Torah: The first warning was to separate from the vicinity of the two hundred and fifty men, 1 whereas the current one was to sepsrate from the vicinity of Korach, Dasan and Aviram. 2
Refer to 16:21:2.1:1.
Oznayim la'Torah (on Pasuk 23): Which also explains why Hashem isued this warning only to Moshe - since Aharon had to remain with the two hundred and fifty men who were burning the Ketores until thr end.
Why did eeverybody have to leave the vicinity of Korach, Dasan and Aviram's dwellings?
Ramban: Refer to 16:26:2:1*.
Seforno: Refer to 16:26:2:3.
Oznayim la'Torah: To demonstrate that they disagreed with them - and they were therefore spared from suffering the same fate. 1
Oznayim la'Torah: Moshe and Aharon's Tefilah "ha'Ish Echad Yecheta ... " therefore worked fro them, but mnot for the two hundred nd fifty men who, not only showed no sign of retracting, but who went on to bring the Ketores. See Oznayom la'Torah on Pasuk 22 DH 'ha'Ish Echad Yechata ... '.
