Note: HaRav Isser Wolfson shlita is a noted talmid chacham, dayan and posek. The shiurim were transcribed by me and reviewed by Rav Wolfson. What you are reading is just an excerpt and not the whole shiur. I have also taken the liberty of making some slight editorial changes to the original version in order to make it read better. This week's excerpt is from Ki Tisa 5764.
The Minchas Chinuch (Mitzvah 364) quotes the Tzlach (Berochos 20) whi says that the Leviim are not included in the parsha of arvus with the rest of Klal Yisroel. The Minchas Chinuch asks on this that we find that Moshe was misvadeh for B’nei Yisroel after the cheit ha'eigal. However, the halacha is that vidui can only be done by one who is embarrassed by the aveirah. If the Tzlach is correct that the Leviim have no arvus, then how could Moshe be misvadeh? Since Moshe had no arvus he should not have been considered responsible for the aveirah and he should have nothing to be embarrassed about?
In Bechukosai (26:42) in the middle of the tochacha HKBH says he will remember the zechus avos. Then in pessukim 26:43-44 the Torah mentions more tochacha along with the idea of “lo mi’astim v’lo gi’altem”. Finally, in possuk 26:45 the Torah mentions the bris rishonim. The Ramban explains that pessukim 26:43-44 refer to the tekufah of Purim and possuk 45 refers to the bris shevatim, which gave us the zechusim needed to rebuild the Bais HaMikdash. The Medrash Shir HaShirim says that even though the neis of Purim happened in Shushan, because of arvus all of Klal Yisroel kept Purim as well. The main difference between the shevatim and the avos is that the avos didn’t have a concept of arvus. Each of the avos were one person, and therefore it was not shayach arvus since you can’t have arvus with one person. The shevatim on the other hand were 12 people and among 12 people you can have arvus. This was the chiddush of the bris hashevatim, the concept of arvus. The bris avos mentioned in 26:42 included everything but arvus. Pesukim 43-44 was a chisaron in arvus and this was fixed thru Purim. Possuk 45 is the bris hashevatim, which is a bris of arvus and thru this the second Bais HaMikdash could be rebuilt.
When the Tzlach said that the Leviim had no arvus, what he meant was that they didn’t need the bris of arvus. After the cheit haeigal, we find that the Leviim killed 3,000 Jews. By doing this they showed they were accepting the idea of arvus without a bris. Moshe also showed this by davening for Klal Yisroel. It was only the rest of Klal Yisroel that needed the bris hashevatim/bris arvus, which they accepted by the tochacha in Bechukosai.