Accomplishing Many Things With Tefillah

My grandfather, the Kretchnifer Rebbe zy”a (quoted in Gilyon Kol Emunah) notes that it seems as if Moshe did not accomplish anything with all of his 515 tefillos. However, the truth is that he accomplished many things. Although he did not merit entering Eretz Yisroel, he did accomplish many other things.

Therefore, Hashem told him not to speak anymore about “this matter.” He was saying that his tefillos would not help for this matter, but they would help for many other things.