Numbers 3:1-4
The Levites
1 This is the list of the family of Aaron and Moses. This was at the time when the Lord spoke to Moses on Sinai mountain.
2 The names of the sons of Aaron were Nadab, Abihu, Eleazar and Ithamar. Nadab was the firstborn son. 3 Aaron anointed them, and he gave authority to them to work as priests. 4 But Nadab and Abihu fell down and died in front of the Lord. That happened when they offered strange fire to the Lord in the Sinai desert. They had no children. So only Eleazar and Ithamar worked as priests while their father Aaron was alive.
3:4We are not sure what ‘strange fire’ was. But we know that it was something wrong that did not please God.