Charles Ellicott Commentary Numbers 9:6

"And there were certain men, who were unclean by reason of the dead body of a man, so that they could not keep the passover on that day: and they came before Moses and before Aaron on that day:" — Numbers 9:6 (ASV)

And there were certain men ... — It has been supposed that the reference is to Mishael and Elzaphan, who appear to have buried their cousins, Nadab and Abihu, about this time (Blunt’s “Script. Coincidences,” pp. 66, 67, 1850). If the consecration of Aaron and his sons began on the first day of the first month (Exodus 40:2; Exodus 40:12), and the death of Nadab and Abihu could not have taken place until the eighth day (Leviticus 9:1; Leviticus 9:12; Leviticus 10:19), since the defilement caused by contact with the dead lasted for seven days (Numbers 19:11), it follows, if this law was already in force, that those who buried Nadab and Abihu must have been unclean on the fourteenth day of the first month.

Professor Blunt also draws a doubtful inference from the identical numbers of the other tribes at the two numberings (one before and the other after this time), from which he concludes that the deaths must have occurred among those belonging to the tribe of Levi, which was not included in the census. Independently of that particular argument, however, the circumstance previously mentioned may fairly be cited as one of the numerous undesigned coincidences with which Holy Scripture abounds.

It may be observed further that, while Moses would naturally be consulted on all doubtful occasions, none would be as likely to approach him with the inquiry contained in Numbers 9:7 as those who had been employed by his direction (Leviticus 10:4) in the burial of Nadab and Abihu. The law contained in Leviticus 7:21 appears to have been understood to refer to all sacrificial meals. The legal uncleanness which disqualified the Israelites for participation in the Passover may be regarded as typical of the moral and spiritual disqualifications which render men unfit for participation in the Lord’s Supper.