Numbers 16:1 Now Korah, the son of Izhar, the son of Kohas, the son of Levi and Dathan and Abiram, the sons of Eliab and On, the son of Peleth, sons of Reuben, took men: 2 And came to Moses 250 princes of the assembly of the Children of Israel, famous renowned men in the congregation. C-MATS
Question: What is different about this incident as compared to other problems the people complained about? In contrast to earlier occasions when the people complained about specific problems — such as a lack of food or water, or the need for a “god” to take Moses’ place as an intermediary between יהוה and Israel — in this incident, there is an outright rebellion, an attempt to overthrow Moses and Aaron as the leaders of the nation. The leader of the rebellion was their cousin and fellow Levite, Korah. Chumash
Question: Why did Korah rebel against Aaron and his sons? Korah rebelled right after the inauguration of the Tabernacle, when Aaron and his sons were designated to replace the firstborn as the only ones who would perform the sacrificial service. This angered Korah, who was himself a firstborn (Exodus 6:21 And the sons of Izhar; Korah and Nepheg and Zichri.), and it was easy for him to enlist two hundred and fifty … leaders of the assembly, who were also firstborn. Dathan, Abiram, and On were from the tribe of Reuben, which had its own reason for resentment, having lost its privileged firstborn status to the offspring of Joseph (Genesis 48:5 And now your two sons, Ephraim and Manasseh, who were born to you in the land of Egypt before I came to you in Egypt, are mine; as Reuben and Simeon are mine, they will be mine.). Other Levites were upset at having been relegated to be mere assistants of the Kohanim. Chumash