Abihu

Abihu was the second son of Aaron and Elisheba, and the brother of Nadab, Eleazar, and Ithamar (Exodus 6:23; Numbers 3:2). He was consecrated as a priest along with his brothers to serve at the tabernacle (Exodus 28:1). Abihu went up Mount Sinai with Moses, Aaron, Nadab and seventy elders of Israel to worship the Lord before He gave the tablets of the Testimony to Moses (Exo.24.1,9).

However, Abihu and his brother Nadab offered unauthorized fire before the Lord, and fire came out from the presence of the Lord and consumed them, and they died (Leviticus 10:1–2; Num.3.4; 26.61). This occurred on the eighth day of the priests' consecration. Aaron and his surviving sons were not allowed to mourn their deaths (Leviticus 10:6).

The sin of Abihu and Nadab was in offering "strange fire" which the Lord had not commanded (Leviticus 10:1). This may refer to offering incense that was not prepared according to God's instructions, or performing this in a wrong manner or at an inappropriate time. Their deaths served as a stern warning against improper worship. After this incident, God gave Aaron further regulations for priestly service and conduct (Leviticus 10:8–11). The genealogies record Aaron's descendants through his other sons Eleazar and Ithamar, since Nadab and Abihu had no children before their untimely deaths (Numbers 3:4; 1 Chronicles 24:1–2).