The Gemara states that if all the preparations are made for a wedding and the father of the bridegroom or the mother of the bride passed away, we place the deceased in a room and the bridegroom and bride marry and consummate the marriage.
When Hashem gave the Torah to the Jewish People, it is said (Shemos 24:10-11) vayiru es Elokei Yisroel visachas raglav kimaaseih livnas hasapir uchietzem hashamayim latohar, viel atzilei bnei yisroel lo shalach yado vayechezu es haelokim vayochlu vayishtu, they saw the G-d of Israel, and under his feet was the likeness of sapphire brickwork, and it was like the essence of the heaven in purity. Against the great men of the children of Israel, He did not stretch out His hand-they gazed at G-d, yet they ate and drank. Rashi (Ibid) quotes the Medrash that states that two of the great men were Nadav and Avihu, and for gazing at HaShem’s Presence, they were liable the death penalty. Hashem did not want to disrupt the festivities of Matan Torah, so He waited until the dedication of the Mishkan.
Elsewhere, (Vayikra 10:4) Rashi writes that Mishael and Eltzafan, the cousins of Nadav and Avihu, were instructed by Moshe to remove the dead bodies of Nadav and Avihu, akin to one who tells his friend, “remove the deceased’s body from before the bride, so as not to spoil the joy of the wedding.” One must wonder why HaShem felt that the joy of Matan Torah should not be disturbed, whereas the festivities for the Inauguration of the Mishkan could be disturbed.
Perhaps the answer to this question can be found in the words of the Gemara (Yoma 86b) that states that the ideal form of repentance is when one returns to the same situation that he was tempted with when he sinned, and in this instance he controls his desires and refrains from sinning. Similarly, the sin of Nadav and Avihu was that when HaShem revealed Himself at Sinai, the Jewish People experienced a high level of spirituality. Nadav and Avihu, however, were not satisfied with that exalted experience, and to satisfy their desire for striving higher on the spiritual ladder, they gazed at the Divine Presence, thus convicting themselves of the death penalty.
Hashem subsequently sought to offer Nadav and Avihu the opportunity for ideal repentance, HaShem chose the setting of the Inauguration of the Mishkan, where, according to the Ramban (Shemos 25:1) the Divine Presence that had reposed on Sinai revealed, now rested discreetly on the Mishkan. Nadav and Avihu, along with the rest of the Jewish People, again experienced a great revelation of the Divine Presence. In their desire to contain themselves, Nadav and Avihu attempted to enter the Holy of Holies with their firepans and offer the Ketores, the most beloved of all sacrifices. They were put to death because HaShem did not desire this service from them. Thus, HaShem felt that this lesson in repentance was justified in disrupting the festivities of inaugurating the Mishkan.
This idea is a powerful lesson in repentance. We are a few days before Rosh HaShanah, when our focus is in bettering ourselves and repenting from our many sins. It is brought in halacha (Mateh Ephraim 619) that one who sheds tears upon hearing the reading in the Torah of the death of Aharon’s sons, Nadav and Avihu, is guaranteed that his children will not die in his lifetime.
Perhaps the reason for this merit is because one who sheds tears over the death of Nadav and Avihu demonstrates that he has internalized the lesson of not succumbing to the temptation of a sin that he has committed previously. Although children may at times die on account of their parents sins, this person deserves that his children shall not die for his previous sins. May we merit this year to truly repent from our sins and that HaShem inscribes us with the righteous of Israel in the Book of Life.