Who was Abihu?
Abihu was the second son of Aaron by Elisheba (Exo. 6:23; Num. 3:2).
With Aaron, Nadab, and the 70 elders, he accompanied Moses up Sinai to a limited distance (Exo. 24:1).
On his death by fire from heaven, in punishment for offering strange fire.
A standing example of that divine wrath which shall consume all who offer God devotion kindled at any other save the one Altar and Offering of Calvary, whereby "He hath perfected forever them that are sanctified."
IBSE, "Isaac" (in the public domain) with minor edits.