Commento su Numeri 9:5

ויעשו את הפסח בראשון, “They prepared the Passover in the first month, etc.” Nachmanides writes that in accordance with the opinion of the sages this was the only time that the Israelites celebrated the Passover during all the years they were in the desert. The reason was that they had uncircumcised slaves and children whom they could not circumcise due to the hazard of infection in the desert conditions. The matter is discussed in Yevamot 72. However, in Sifri Behaalotcha 67 the word בראשון is understood as a criticism of the Children of Israel for having celebrated the Passover only on that occasion. Similarly, Amos 5,25, where the prophet speaks of “did you offer sacrifice and oblation to Me those forty years in the wilderness?” is also seen as a criticism of the Israelites for not offering all these sacrifices. This criticism is based on the unnecessary words “in the first month, the fourteenth of the month, in the evening in the desert of Sinai.” It would have sufficed for the Torah to write that the Israelites offered the Passover in accordance with the rules laid down by G’d. The additional details provided are a hint that this was the one and only time the people did observe the Passover. (Thus far Sifri).
The reason that the Torah saw fit to write this passage at this point was that the inauguration of the Tabernacle and the Altar took place in the first month (of the second year); this was the month the Levites were set apart. Seeing that in connection with the Passover observance the Torah wrote (Exodus 12,25) “it will be when you come into the land, etc.,” and in Exodus 13,11 the Torah also appeared to tie the observance of the Passover to the Israelites coming to the Holy Land, the Torah here had to legislate its observance now as otherwise the people would have thought that the desert was not a suitable location for offering the Passover.

ויעשו את הפסח, “they performed the ritual of the Passover;” according to Rabbi Yossi in the Tossephta, this was the only time in all the years that the Israelites wandered in the desert that the Passover was actually observed. The reason for this was that at the time described they were encamped in a location where it was possible to perform circumcisions without endangering the lives of the infants being circumcised. This has been explained at the beginning of the Book of Joshua where a mass circumcision took place of all the people who had been born after the Exodus and who could not have been circumcised on account of the danger to the lives of these infants.