Or HaChaim on Numbers 16:21/אור החיים על במדבר ט״ז:כ״א

1 הבדלו מתוך העדה הואת "separate yourselves from this congregation, etc." This instruction was not addressed to Moses and Aaron as they did not have anything to fear from the attribute of Justice. Nothing would happen to them even if they remained standing close while G'd killed the whole community. I can give you proof of this when you consider that Aaron who was part of that group when he offered his incense remained unharmed while the earth opened underneath Korach and his family and swallowed them. G'd's instructions were addressed to the other righteous men in the congregation, people such as Joshua and Caleb as well as the families of Moses and Aaron. G'd prefaced His instructions to Moses and Aaron with the word לאמור. If the instructions had applied to Moses and Aaron themselves the word לאמור would have confused them. G'd addressed the righteous people who had to demonstrate by separating themselves that they disassociated themselves from Korach and his associates.

2ואכלה אותם כרגע, "and I will consume them in a moment." Why did G'd add the word כרגע, "in a moment?" If all G'd wanted to inform us of was that He possessed the power to wipe out 600.000 people in a flash, He had already told us this in Exodus 33,5 "for if I go up in your midst for one moment, I shall consume you."

3It appears according to the Midrash quoted by Rashi on verse 22,4 that this was already the fourth time the Israelites sinned and that the uprising of Korach occurred after the sin of the spies. I have explained there that the decree that the Israelites would die in the desert remained in effect but that Moses' prayer in this instance only prevented G'd from destroying the people all at once instead of over an extended period of time. In view of all this, the congregation we speak about here was already guilty of death in the desert. The Torah therefore reintroduces the threat to kill the whole people at once. This provides us with an answer as to why G'd would decree death for the vast majority of the people who had not been part of this uprising at all. Moses himself speaks about a single person sinning and the whole community becoming the target of G'd's anger (verse 22). Actually, as we demonstrated, the people were under sentence of death regardless of whether they associated themselves with Korach's rebellion or not. We have learned in Shabbat 32 that Satan is always especially active when there is danger. At such times even a relatively mild offence such as talking during the prayers is considered serious enough to free soldiers from participating in expansionary wars lest they endanger themselves needlessly on account of that sin. It is clear that the sin of talking during prayers is not a captial offence. It is only the fact that during war the angel of death is especially active which makes the unatoned for sin of talking during prayers potentially lethal. In our situation, the fact that the people were under sentence of death anyway would have made the angel of death eager to kill them at once if they had not first dissociated themselves from Korach.

4After looking further into this matter I have realised that ordering the people to separate themselves from Korach's group could be perceived as therapy for the Jewish people. Had G'd not given these instructions, only those righteous amongst the Jewish people who had not yet been included in the decree that they would die in the desert would have escaped becoming victims of the angel of death at that time. By giving this instruction G'd actually gave the Israelites an opportunity to save themselves from imminent death seeing that all of them had a minor share in Korach's sin because they had not protested it. In fact, failure to protest what Koarch was trying to do was equivalent to being a passive supporter of Korach. G'd instructed Moses and Aaron to separate the righteous and thus enable him to pray on their behalf to ask for them to be spared, invoking his own merit. This is why G'd said to Moses: "tell the whole congregation 'get up from from around the dwelling of Korach, Datan and Aviram'" (verse 24). If we accept this approach the word הבדלו in our verse was meant to alert Moses and Aaron to pray, seeing there was no need for Moses and Aaron to separate themselves in order not to become victims of Korach's sin. Perhaps this is what G'd alluded to when He said לאמור, meaning that the whole purpose of G'd speaking to them at this juncture was לאמור, in order that Moses and Aaron start to pray as we indeed find that they did in verse 22. If we accept this interpretation we need not understand that G'd referred to Moses and Aaron removing their families from around the tent of Korach.