Numbers 26:61

26:61 But Nadab and Abihu died when they offered strange fire ¹  before the Lord.

Numbers 3:2

3:2 These are the names of the sons of Aaron: Nadab, the firstborn, and Abihu, Eleazar, and Ithamar.

Numbers 26:60

26:60 And to Aaron were born Nadab and Abihu, Eleazar and Ithamar.

[26:61]  ¹ tn The expression אֵשׁ זָרָה (’esh zarah, “strange fire”) seems imprecise and has been interpreted numerous ways (see the helpful summary in J. E. Hartley, Leviticus [WBC 4], 132-33). The infraction may have involved any of the following or a combination thereof: (1) using coals from some place other than the burnt offering altar (i.e., “unauthorized coals” according to J. Milgrom, Leviticus [AB], 1:598; cf. Lev 16:12 and cf. “unauthorized person” [אִישׁ זָר, ’ish zar] in Num 16:40 [17:5 HT], NASB “layman”), (2) using the wrong kind of incense (cf. the Exod 30:9 regulation against “strange incense” [קְטֹרֶת זָרָה, qÿtoret zarah] on the incense altar and the possible connection to Exod 30:34-38), (3) performing an incense offering at an unprescribed time (B. A. Levine, Leviticus [JPSTC], 59), or (4) entering the Holy of Holies at an inappropriate time (Lev 16:1-2).