Or HaChaim on Numbers 9:13/אור החיים על במדבר ט׳:י״ג

1 והאיש אשד הוא טהור, As to the man who is ritually pure, etc. Why did the Torah delay informing us about the penalty for people who deliberately fail to observe the Passover legislation until now? Why has this not been spelled out in Parshat Bo where the legislation was spelled out? We find a debate in Pessachim 93 between Rabbi and Rabbi Natan concerning whether a person who has failed to observe the Passover both on the 14th of Nissan and the 14th of Iyar incurs the prescribed penalty or whether the Karet penalty applies only if one has deliberately failed to observe the Passover on the 14th of Nissan. Rabbi holds that deliberate failure to observe either Passover results in that penalty, whereas Rabbi Natan holds that there is no Karet penalty for failure to observe the second Passover seeing that the Torah does not mention this penalty in that context. Rabbi Chanina son of Akiva holds that one is not even guilty of the karet penalty for failure to observe the Passover on the 14th of Nissan unless one had also failed to observe it on the 14th of Iyar. All three scholars cite the same verse to support their respective opinions. If the Torah had informed us about the penalty for deliberate non-observance in Parshat Bo, it would not have been possible for the three scholars to hold three different views on the subject.