Who are “your brothers” to whom Moses is referring?
Leviticus 10:6 (ESV)
6And Moses said to Aaron and to Eleazar and Ithamar his sons, “Do not let the hair of your heads hang loose, and do not tear your clothes, lest you die, and wrath come upon all the congregation;but let your brothers, the whole house of Israel, bewail the burning that the LORD has kindled.
The word brothers was used in Leviticus 10:4 to refer to Nadab and Abihu. On this occasion it refers to the nation of Israel. Even though the priests were not allowed to mourn, the Lord allowed the people to grieve.
6 And Moses said to Aaron and to Eleazar and Ithamar his sons, “Do not let the hair of your heads hang loose, and do not tear your clothes, lest you die, and wrath come upon all the congregation; but let your brothers, the whole house of Israel, bewail the burning that the LORD has kindled.