allah, the exalted, says:
"so stand (ask allah to make) you (muhammad (pbuh)) firm and straight (on the religion of islamic monotheism) as you are commanded...'' (11:112)
"verily, those who say: `our rubb is allah (alone),' and then they stand firm, on them the angels will descend (at the time of their death) (saying): 'fear not, nor grieve! but receive the glad tidings of jannah which you have been promised! we have been your friends in the life of this world and are (so) in the hereafter. therein you shall have (all) that your inner-selves desire, and therein you shall have (all) for which you ask. an entertainment from (allah), the oft-forgiving, most merciful.''' (41:30-32)
"verily, those who say: `our rubb is (only) allah,' and thereafter stand firm and straight (on the islamic faith of monotheism), on them shall be no fear, nor shall they grieve. such shall be the dwellers of jannah, abiding therein (forever), - a reward for what they used to do.'' (46:13,14)
85. sufyan bin `abdullah (may allah be pleased with him) reported: i said, "o messenger of allah, tell me something of islam which i will not ask anyone else about it.'' he (pbuh) said, "say, `i believe in allah' and then be steadfast".
commentary: steadfastness means adhering firmly to the injunctions of islam, to act upon what is ordained and avoid what is prohibited, to perform dutifully orders in respect of obligations and what is regarded desirable and avoid what is unlawful. faith is not a mere expression of shahadah. the real faith is one which is coupled with its actual practice because practice of religion is in fact the fruit of faith. a tree which does not bear any fruit, has no value, similarly; faith becomes meaningless without practice. steadfastness is the mark of perfect faith.
86. abu hurairah (may allah be pleased with him) reported: messenger of allah (pbuh) said, "follow the right path of faith strictly, and be steadfast; and keep in mind that none of you can achieve salvation through his (good) actions.'' someone asked, "not even you, o messenger of allah?'' he (pbuh) said, "not even me, unless allah grants me his mercy and grace".
commentary: 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.