Concerning Allah's statement,
﴿إِنَّ الْحَسَنَـتِ يُذْهِبْنَ السَّـيِّئَـتِ﴾
(Verily, the good deeds remove the evil deeds.) This is saying that the performance of good deeds is an expiation of previous sins. This has been mentioned in a Hadith recorded by Imam Ahmad and the Sunan Compilers, that the Commander of the faithful, `Ali bin Abi Talib, said, "Whenever I used to hear a narration from the Messenger of Allah (), Allah would cause me to benefit by it however He willed. If anyone informed me of any statement that he said, I would make him swear (by Allah) that the Prophet said it. If he swore by Allah, then I would believe him. Abu Bakr once told me -- and Abu Bakr was truthful -- that he heard the Messenger of Allah say,
«مَا مِنْ مُسْلِمٍ يُذْنِبُ ذَنْبًا فَيَتَوَضَّأُ وَيُصَلِّي رَكْعَتَيْنِ إِلَّا غُفِرَ لَه»
(There is not any Muslim who commits a sin, then he makes Wudu' and prays two units of prayer, except that he will be forgiven (that sin).) In the Two Sahihs it is recorded that the Commander of the faithful, `Uthman bin `Affan made Wudu' for the people (to see), just like the Wudu' of the Messenger of Allah . Then he said, "I saw the Messenger of Allah make Wudu' like this, and he said,
«مَنْ تَوَضَّأَ وُضُوئِي هَذَا ثُمَّ صَلَّى رَكْعَتَيْنِ لَا يُحَدِّثُ فِيهِمَا نَفْسَهُ غُفِرَ لَهُ مَا تَقَدَّم مِنْ ذَنْبِه»
(Whoever makes Wudu' like this Wudu' of mine, then he prays two units of prayer in which he does not speak to himself, he will be forgiven for his previous sins.) In the Sahih it is recorded that Abu Hurayrah said that the Messenger of Allah said,
«أَرَأَيْتُمْ لَوْ أَنَّ بِبَابِ أَحَدِكُمْ نَهْرًا غَمْرًا، يَغْتَسِلُ فِيهِ كُلَّ يَوْمٍ خَمْسَ مَرَّاتٍ، هَلْ يُبْقِي مِنْ دَرَنِهِ شَيْئًا؟»
(Do you think that if there was a flowing river at the door of anyone of you and he bathed in it five times every day, would there be any dirt left on him) They said, "No, O Messenger of Allah!'' He () said;
«كَذَلِكَ الصَّلَوَاتُ الْخَمْسُ يَمْحُو اللهُ بِهِنَّ الذُّنُوبَ وَالْخَطَايَا»
(This is like the five daily prayers, for Allah uses them to wipe away the sins and wrongdoings.) Muslim recorded in his Sahih that Abu Hurayrah said that the Messenger of Allah used to say,
«الصَّلَوَاتُ الْخَمْسُ، وَالْجُمُعَةُ إِلَى الْجُمُعَةِ، وَرَمَضَانُ إِلَى رَمَضَانَ، مُكَفِّرَاتٌ لِمَا بَيْنَهُنَّ مَا اجْتُنِبَتِ الْكَبَائِر»
(The five daily prayers, Jumu`ah (Friday prayer) to Jumu`ah and (the fast of) Ramadan to Ramadan are expiations for whatever sins were committed between them, as long as you stay away from the major sins.) Al-Bukhari recorded Ibn Mas`ud saying that a man kissed a woman (who was not his relative or wife). He then came to the Prophet and informed him about the incident. Thus, Allah revealed,
﴿وَأَقِمِ الصَّلَوةَ طَرَفَىِ النَّهَارِ وَزُلَفاً مِّنَ الَّيْلِ إِنَّ الْحَسَنَـتِ يُذْهِبْنَ السَّـيِّئَـتِ﴾
(And perform Salah, at the two ends of the day and in some hours of the night. Verily, the good deeds remove the evil deeds.)﴿11:114﴾ The man then said, "O Messenger of Allah, is this only for me'' The Prophet replied,
«لِجَمِيعِ أُمَّتِي كُلِّهِم»
(This is for all of my (Ummah) followers.) Al-Bukhari recorded this narration in the Book of Prayer as well and the Book of Tafsir. Imam Ahmad recorded that Ibn `Abbas said that a man came to `Umar and said that a woman came to do business with him. During the course of their business, he took her into his place and did everything with her except the actual act of sexual intercourse. `Umar said, "Woe unto you! She probably was a woman whose husband is away (fighting) in the path of Allah.'' The man said, "Of course she was.'' `Umar then said, "Go to Abu Bakr and ask him about this.'' The man went to Abu Bakr and asked him about the matter. Abu Bakr said, "She probably was a woman whose husband is away (fighting) in the path of Allah,'' just as `Umar had said. Then he went to the Prophet and told him the same story. The Prophet said,
«فَلَعَلَّهَا مُغِيبَةٌ فِي سَبِيلِ الله»
(She probably was a woman whose husband is away (fighting) in the path of Allah.) Then a verse of Qur'an was revealed,
﴿وَأَقِمِ الصَّلَوةَ طَرَفَىِ النَّهَارِ وَزُلَفاً مِّنَ الَّيْلِ إِنَّ الْحَسَنَـتِ يُذْهِبْنَ السَّـيِّئَـتِ﴾
(And perform the Salah, at the two ends of the day and in some hours of the night. Verily, the good deeds remove the evil deeds.) The man then said, "O Messenger of Allah! Is this verse only for me, or does it apply to all of the people in general'' `Umar then struck the man on his chest with his hand and said, "No, rather it is for all of the people in general.'' Then the Messenger of Allah said,
«صَدَقَ عُمَر»
(`Umar has spoken the truth.)
﴿فَلَوْلاَ كَانَ مِنَ الْقُرُونِ مِن قَبْلِكُمْ أُوْلُواْ بَقِيَّةٍ يَنْهَوْنَ عَنِ الْفَسَادِ فِى الاٌّرْضِ إِلاَّ قَلِيلاً مِّمَّنْ أَنجَيْنَا مِنْهُمْ وَاتَّبَعَ الَّذِينَ ظَلَمُواْ مَآ أُتْرِفُواْ فِيهِ وَكَانُواْ مُجْرِمِينَ - وَمَا كَانَ رَبُّكَ لِيُهْلِكَ الْقُرَى بِظُلْمٍ وَأَهْلُهَا مُصْلِحُونَ ﴾
(116. If only there had been among the generations before you persons having wisdom, prohibiting (others) from Fasad (corruption) in the earth, except a few of those whom We saved from among them! Those who did wrong pursued the enjoyment of good things of (this worldly) life, and were criminals.) (117. And your Lord would never destroy the towns wrongfully, while their people were doers of good.)