Abihu: Son of Aaron
Source: Nav
Exodus 6:23
And Aaron married Elisheba, the daughter of Amminadab and sister of Nahshon, and she bore him Nadab and Abihu, Eleazar and Ithamar.
Numbers 3:2
These are the names of the sons of Aaron: Nadab the firstborn, then Abihu, Eleazar, and Ithamar.