Moses
Numbers 9:13ESV·traditional attribution

But if anyone who is clean and is not on a journey fails to keep the Passover, that person shall be cut off from his people because he did not bring the LORD’s offering at its appointed time; that man shall bear his sin.

Matthew Henry Presbyterian @wholebiblehenry

Here we have, I. An order given for the solemnization of the passover, the day twelvemonth after they came out of Egypt, on the fourteenth day of the first month of the second year, some days before they were numbered, for that was done in the beginning of the second month. Observe, 1.

Commenting on Numbers 9:1-14

John Gill Reformed Baptist @doctorgill

And if a stranger shall sojourn among you, and will keep the passover unto the Lord,.... Then he must become a proselyte of righteousness, and be circumcised, or otherwise be might not eat of the passover, Exo 12:48; Ben Gersom interprets this of the second passover, and of a proselyte that was not obliged to the first, he not being then a proselyte, but became...

Jamieson-Fausset-Brown Reformed @jfbcommentary

A SECOND PASSOVER ALLOWED. (Num 9:6-14) there were certain men, who were defiled by the dead body of a man--To discharge the last offices to the remains of deceased relatives was imperative; and yet attendance on a funeral entailed ceremonial defilement, which led to exclusion from all society and from the camp for seven days.

Commenting on Numbers 9:6-14