פסח שני
Parshat בהעלותך speaks of the case of פסח שני. There were a number of Jews in the desert who were unable to offer the קרבן פסח on the fourteenth of Nissan because they had come in contact with the dead.
There are various interpretations as to who exactly was טמא מת, and could not offer the Pesach sacrifice. Some say that those who handled the burial of Nadav and Avihu were still טמא by the fourteenth. Others say that there were members of each tribe charged with carrying the remains of the sons of Yakov, so they were defiled.
There is another opinion that certain Jews had to deal with a מת מצוה, a Jewish corpse that had nobody to bury it. The מת מצוה is such an important Mitzva that even the כהן גדול or נזיר had to defile themselves for it.
What we also see from this case, is the enthusiasm the Jewish people had for Pesach and its sacrifice. They realized that it was a significant affirmation of Hashem’s miracles and protection.
Hashem told Moshe that there would be a make-up date a month later on the fourteenth of Iyar. But this was limited to those people who demonstrated their disappointment at not doing the sacrifice at its appropriate time.
If someone could have done it in Nissan, but didn’t want to strain himself to do the Mitzva, he does not get the make-up date.
We see from here how important it is to do Mitzvot with enthusiasm and excitement. If we don’t, we may not have the chance to make it right later.