Levi was God's tribe, a tribe that was to have no inheritance with the
rest in the land of Canaan, and therefore was not numbered with the
rest, but by itself; so it had been numbered in the beginning of this
book at Mount Sinai, and therefore came not under the sentence passed
upon all that were then numbered, that none of them should enter Canaan
but Caleb and Joshua; for of the Levites that were not numbered with
them, nor were to go forth to war, Eleazar and Ithamar, and perhaps
others who were above twenty years old then (as appears, ch. iv. 16,
28), entered Canaan; and yet this tribe, now at its second numbering,
had increased but 1000, and was still one of the smallest tribes.
Mention is made here of the death of Nadab and Abihu for offering
strange fire, as before of the sin and punishment of Korah, because
these things happened to them for ensamples.