This Hadith tells us that although the importance of Faith and its practice is beyond any shadow of doubt, because this is the only way to attain His Favours and Blessings, but one should not entirely depend upon practice only because any shortcoming (which one does not even know) can ruin a good deed. It is, therefore, essential that we also pray that our good deeds are accepted by Allah and that He grants us His Infinite Mercy and sincerity because even the greatest noble deed is invalid without it.