When Korah and his congregation complained about the status of Moses and Aaron, Moses instructed them to wait until morning, at which time God would disclose whom He selected. The Sages provide reasons for Moses’ postponing the matter until the next morning.

“He spoke to Korah and to his entire congregation, saying: In the morning the Lord will disclose who is His, and who is holy; and will bring him near to Him” (Numbers 16:5). What did Moses see that led him to say “morning”? Moses said: Perhaps they said this matter as a result of eating and drinking. Moses said to himself: Perhaps in the meanwhile [the effects of the food and drink will subside and] they will repent. Therefore, the verse states: “In the morning the Lord will disclose.” Moses told Korah: I do not have license to enter before Him now. It is not that there is eating and drinking before Him [and therefore He is too occupied to hear our claims now]. But we may not enter on our account, because we ate and drank. Alternatively, Moses said to them: The Holy One, Blessed be He, established boundaries in His world; can you mix day and night?.... Just as He distinguished between light and darkness for the constant function of the world, so He distinguished between Israel and the nations…and so He designated Aaron as High Priest, as it is stated: “Aaron was set apart to sanctify him as most holy” (I Chronicles 23:13). If you can nullify that distinction between light and darkness, you can nullify this distinction between Aaron and his sons, the priests; and the rest of the people. (Bemidbar Rabba 18)