Sefer Yismach Yisroel quotes his father, Rav Yechiel of Alexander zy’a, as explaining this pasuk by citing Sefarim Hakedoshim that say that one of the prerequisites for teshuva is ‘kabbalah’, i.e., accepting rebuke and committing to improve from now on.
This is seen from Rabenu Yona’s explanation of the Mishnah (Avos 3:9) that says that if one’s actions are more than his wisdom, both will last. He explains this to mean that if one accepts to obey Hashem and do His mitzvos, even if his wisdom is limited and he doesn’t know about all of them, it is considered as if he already did all the mitzvos. This is seen in the pasuk in Daniel (10:2): ‘From the first day when you gave to your heart…’ This means that as soon as one commits in his heart to perform all the mitzvos, it is considered as if he already did them.
This helps us understand the Gemara (Brachos 33B) regarding the verse: ‘And now, Yisroel, what does Hashem, your G-d, ask of His nation? Only to fear Him…’ The Gemara asks: ‘Is fear of Heaven a small thing?’ It answers: ‘For Moshe, it is a small thing.’ This is hard to understand as this mitzvah is given to all of Klal Yisroel, not just Moshe Rabenu!
The Yismach Yisroel explains that when the pasuk says that all one needs to do is fear Hashem, it means that one merely has to make a kabbalah to obey Him and do His mitzvos. The Gemara then asks if this is a small thing. Is making a genuine commitment really that easy? It answers that, yes, it is for ‘Moshe’. In this context, the Gemara uses the word ‘Moshe’ to mean that when the nation has a leader like Moshe Rabenu, who rebukes them and teaches them the right way, it is, in fact, easy to follow his words and accept to properly serve Hashem.
