Dear Rabbi Kornfeld:
The Gemara says here that Tefila is greater than Maasim Tovim since when Moshe Rabbeinu desired to be allowed into Eretz Yisrael, he davened to this effect and was answered in a partial manner in that while Hash-m would not retract His decree that Moshe not enter, at least he would be permitted to see it from afar. Moshe's Maasim Tovim had not effected this, only his Tefila has accomplished it; hence, the Gemara's assertion that Tefila is greater.
Yet, we find in the Torah (Shemos 14) at Keriyas Yam Suf that Moshe was told that the moment was not one for Tefila; rather the people had to do something, namely, plunging into the Yam and this act of Emunah would get them through. Rashi there (posuk 15) tell us that Hash-m said that it was not the time for Tefila at length. Or Hachaim adds that Tefila would not be enough, they needed a tangible zechus which would be the willingness to plunge into the sea in carrying out Hash-m's command. That display of Emunah was what was needed in order that the Nes of Kriyas Yam Suf take place.
My question is, why in Devarim 3 the Maasim of Moshe which no doubt contained tremendous zechuyos were not enough to allow him to enter Eretz Yisael, only Tefila accomplished something in that he was at least able to see it.Thus the Gemara says that Tefila is greater than Maasim. Yet, Hash-m advised against Tefila in Shemos 14; an act of faith was required, which seems to suggest that Maasim are greater than Tefila.
Tosfos here (DH Gedolah) writes that the Gemara is proving that Tefilah with Ma'asim Tovim is greater than Tefilah alone.