Allah mentioned the two groups of His allies - those who strive moderately, and the forerunners - in the sura called Fatir, saying:
[Then, we passed the book on to those whom we chose from among our slaves. Among them were those who oppressed themselves (i.e. by disobeying Allah), those who did good in moderation, and forerunners for good with the permission of Allah, that is the greatest of honors. * Gardens of permanence which they enter. Therein they are dressed in bands of gold and pearls, and their clothes are made of silk. * They will say: Praise be to Allah who has removed from us the fear (of falling into the forbidden during the life of this world), our Lord is oft-forgiving, appreciative. * He who settled us in the home of permanence and honor, no weariness will touch them therein, neither spiritual nor physical.] Qur'an 35/32-35
The three groups mentioned in these verses are the nation of Muhammad specifically, since they are the ones referred to in the phrase: Then, we passed the book on to those whom we chose from among our slaves.
The nation of Muhammad are the ones who were made to inherit the book after the previous nations, as a nation, and this does not refer specifically to those who memorize the Qur'an. Rather, everyone who believes in the Qur'an is one of this group, and Allah divided them into oppressors of themselves, doers of good in moderation, and forerunners. This is unlike the division mentioned in the verses quoted at the beginning of Chapter 4, which includes all of the previous nations: their disbelievers and their believers. This division, on the other hand, is only for the nation of Muhammad. Thus, the oppressors of themselves are those who intentionally commit major sins, the doers of good in moderationare those who perform the obligatory and avoid the forbidden, and the forerunners for good are those who fulfill the obligatory, and make extra effort with the nawaafil(nonobligatory actions pleasing to Allah), just as they were described in the abovementioned verses. Whoever repents from his sin - whatever his sin may be - a true and acceptable repentance, is not removed from being among the forerunners for good or the doers of good in moderation, as in Allah's statement:
[And rush to forgiveness from you Lord and a garden whose width like the heavens and the earth which has been prepared for the pious. * Those who spend in good times and in bad, who refrain themselves when enraged, and who are forbearing with people. Allah loves the doers of good. * Those who, when they commit some outrage or oppress themselves (by disobedience to Allah), remember Allah and seek His forgiveness for their sins. And who can forgive sins except for Allah? And they do not persist in the wrong which they did after they know. * Their reward is forgiveness from their Lord and gardens under which rivers flow, to dwell therein forever, and that is the reward of those who strive.] Qur'an 3/133-136
The statement of Allah:
[Gardens of permanence which they will enter...] Qur'an 13/23
is cited by the followers of the Sunnah as proof that no one of the people of tauhid (correct monotheism) will stay in the hell-fire forever.
As for the punishment of many of the doers of major sins among the Muslims in the fire, this is something about which so many hadith have been narrated from the Prophet so as to leave no doubt whatsoever. In the same way, their eventual release from the fire has been documented beyond any doubt in the sunnah of the Prophet (sas), as well as the intercession of the Prophet for the sinners of his nation, and their release from the fire after his pleading on their behalf, or the pleading of others. Thus, whoever says: "One who commits a major sin is in the fire ever", bending the meaning of the verses mentioned earlier to say that the forerunners are the only ones to enter paradise, and both those who do good in moderation and the oppressors of themselves will never enter it, as some of the Mu'tazilah have said, they are one extreme, and are faced by the Murji'a who went off in the other direction refusing to say definitely that any of the major sinners may enter the fire, imagining that all of the major sinners may enter paradise without punishment. Both of these views are in contradiction with the sunnah of the Prophet which has been narrated from so many sources as to leave no doubt whatsoever, and are in contradiction with the unanimous consensus of the early generations of Muslims, and the Imams of Islam.
Two verses from the Qur'an show clearly the falsehood of the two positions propagated by the Mu'tazilah, and the Murji'a:
[Verily Allah does not forgive the associating of partners with Him, and He forgives anything less than that to those whom He wishes.] Qur'an 4/48
Allah here informs us that he does not forgive associationism (shirk), and that He forgives what is less than that to those whom He wishes. It is incorrect to say that the one intended by this verse are those who have repented, as the Mu'tazilah have said, because Allah forgives even associationism from one who repents from it. Allah also forgives all other sins from one who repents from them a valid repentance, so there is also no sense in the phrase to those whom He pleases if we imagine the verse to be speaking about those who have repented. (Thus, it is clear that this verse refers to those who died without ever making repentance from their sins: if their sin was associationism, it can never be forgiven, and if it was less than that, Allah will forgive them from those whom He pleases.) This is why when Allah mentioned the forgiveness of those who have repented, He said:
[Say: O, my slaves who have transgressed against your selves, do not despair of the mercy of Allah, verily, Allah forgives all sins, and Allah is the Forgiving, the Merciful.] Qur'an 39/53
In this verse, Allah has made His forgiveness general to all sins and without restrictions or qualifications. Allah forgives his slave for any sin from which he has repented. Whoever repents from associationism, is forgiven by Allah, and whoever repents from major sins, Allah forgives him; whatever sin someone commits and then repents from it, is forgiven by Allah.
Thus in the verse about repentance (39/53 above) forgiveness was given in general and without restrictions, whereas in the previous verse (4/48 above), forgiveness was restricted and conditional. Associationism was specifically excluded in that it can not be forgiven, and the forgiveness of lesser sins was made conditional on the decision of Allah. This shows clearly the error of the position of those who assign Allah's forgiveness to all sins, and that associationism in the verse indicates something even greater than that, such as total disbelief in the Creator, or who allow the possibility that all sinners may escape punishment. If it were so, Allah would not have mentioned that He forgives some and not others, and if every oppressor of himself was forgiven all of his sins, without repentance or good deeds to wipe out the bad, He would not have made their forgiveness conditional on His decision.
[He forgives anything less than that to those whom He wishes.] Qur'an 4/48
is proof that Allah will forgive some and will not forgive others (because otherwise this phrase would have no meaning or use, and it is not allowed to say that there are words in the Book of Allah which have no significance.) thereby invalidating the negation of punishment from all sinners of the Muslim nation.