Man is a human being and hence prone to mistakes, but the sensible one is he who recognizes his mistake, repents from it and strives to reform himself. Rasulullah (Sallallahu Alaihi Wasallam) said:

عَنْ أَنَسٍ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم كُلُّ بَنِى آدَمَ خَطَّاءٌ وَخَيْرُ الْخَطَّائِينَ التَّوَّابُونَ (ابن ماجه. مشكاة)

Hadhrat Anas (RA) narrated that Rasululah (Sallallahu Alaihi Wasallam) said: “Every person is a mischief-maker and the best mischief-maker is he who repents in abundance” (Ibn Majah, Mishkaat)

The most important thing in this is that a person should never consider his sin as ordinary. Imaam Bukhari (RA) quoted a Hadith on the authority of Abdullah bin Anas (RA):

إِنَّ الْمُؤْمِنَ يَرَى ذُنُوبَهُ كَأَنَّهُ قَاعِدٌ تَحْتَ جَبَلٍ يَخَافُ أَنْ يَقَعَ عَلَيْهِ ، وَإِنَّ الْفَاجِرَ يَرَى ذُنُوبَهُ كَذُبَابٍ مَرَّ عَلَى أَنْفِهِ. (بخاري)

“A believer considers his sins as if he were sitting under a mountain which, he is afraid may fall on him; whereas the wicked person considers his sins as flies passing over his nose and he just drives them away”. (Bukhari)

So, it is necessary for a believer to repent before Allah and after that resolve firmly to desist from all kinds of sins. What a favour this is from Allah that He Himself prepares His slaves to perform Tawbah, in spite of that fact that His grandeur is Ghani (The Self Sufficient, without want) and anyone’s sins don't concern Him anyway. If the whole world gets submerged into the sins, it will in no way matter Allah, but it is His Mercy and Kindness that He Himself induces his slaves to perform Tawbah and narrates His promises in this respect and also expresses His happiness. Look and contemplate on the following Aayaat (verses) how mercifully Allah Ta’ala invites his slaves towards Tawbah and assures His forgiveness.

اسْتَغْفِرُوا رَبَّكُمْ إِنَّهُ كَانَ غَفَّارًا

“Ask forgiveness of your Lord, surely He is the most Forgiving.” (71:10)

Again, He says at another place:

وَمَنْ يَعْمَلْ سُوءًا أَوْ يَظْلِمْ نَفْسَهُ ثُمَّ يَسْتَغْفِرِ اللَّهَ يَجِدِ اللَّهَ غَفُورًا رَحِيمًا

And whoever does evil or acts unjustly to his soul, then asks forgiveness of Allah, he shall find Allah Forgiving, Merciful. (4:110)

While commenting on this Aayat Allaama Shabbir Ahmad Uthmani (RA) writes:

By سوء and ظلم the minor and major sins are meant or سوء means those sins which agonise others e.g., to defame someone; and ظلم is— the evilness of which remain with ones own self only. Anyway, of whichever nature the sin may be, its cure is ‘Istigfaar’ (to ask forgiveness) and Tawbah (repentance). Allah Ta’ala forgives ones sins if he repents. If some people prove innocence of a criminal deliberately by fraud or prove him guiltless by mistake, it cannot reduce his crime, but if he repents, he can be forgiven.

وَهُوَ الَّذِي يَقْبَلُ التَّوْبَةَ عَنْ عِبَادِهِ وَيَعْفُو عَنِ السَّيِّئَاتِ وَيَعْلَمُ مَا تَفْعَلُونَ ()

“And He it is Who accepts repentance from His servants and pardons the evil deeds and He knows what you do”. (42:25)

قُلْ يَا عِبَادِيَ الَّذِينَ أَسْرَفُوا عَلَى أَنْفُسِهِمْ لَا تَقْنَطُوا مِنْ رَحْمَةِ اللَّهِ إِنَّ اللَّهَ يَغْفِرُ الذُّنُوبَ جَمِيعًا إِنَّهُ هُوَ الْغَفُورُ الرَّحِيمُ

“Say: O my servants! who have acted extravagantly against their own souls, do not despair of the mercy of Allah; surely Allah forgives the faults altogether; surely He is the Forgiving the Merciful”. (39:53)

أَفَلَا يَتُوبُونَ إِلَى اللَّهِ وَيَسْتَغْفِرُونَهُ وَاللَّهُ غَفُورٌ رَحِيمٌ

“Will they not then turn to Allah and ask His forgiveness? And Allah is Forgiving, Merciful”. (5:74)

أَلَمْ يَعْلَمُوا أَنَّ اللَّهَ هُوَ يَقْبَلُ التَّوْبَةَ عَنْ عِبَادِهِ وَيَأْخُذُ الصَّدَقَاتِ وَأَنَّ اللَّهَ هُوَ التَّوَّابُ الرَّحِيمُ

“Do they not know that Allah accepts repentance from His servants and takes the alms, and that Allah is the Oft-returning (to mercy), the Merciful?” (9:104)

وَإِنِّي لَغَفَّارٌ لِمَنْ تَابَ وَآمَنَ وَعَمِلَ صَالِحًا ثُمَّ اهْتَدَى

“And most surely I am most Forgiving to him who repents and believes and does good, then continues to follow the right direction”. (20:82)

Allaama Shabbir Ahmad Uthmani (RA) writes in its commentary:

How big a criminal may be, if he repents by heart and adopts the path of belief and righteousness and further remains steadfast on it until he dies, there will be no dearth of forgiveness and mercy from Allah.

There are number of Aayaat that mention this topic but here only few have been quoted. Now, some Ahaadith are being mentioned below:

عَنْ أَبِى مُوسَى عَنِ النَّبِىِّ صلى الله عليه وسلم قَالَ إِنَّ اللَّهَ عَزَّ وَجَلَّ يَبْسُطُ يَدَهُ بِاللَّيْلِ لِيَتُوبَ مُسِىءُ النَّهَارِ وَيَبْسُطُ يَدَهُ بِالنَّهَارِ لِيَتُوبَ مُسِىءُ اللَّيْلِ حَتَّى تَطْلُعَ الشَّمْسُ مِنْ مَغْرِبِهَا (مسلم)

Hadhrat Abu Musa (RA) narrated that Rasulullah (Sallallahu Alaihi Wasallam) said, “Allah spreads His hand during the night so that the one who committed sins during the day may repent, and spreads His hand during the day so that the one who committed sins during the night may repent (this will continue) until the sun rises from the west” (Muslim)

عَنْ عَائِشَةَ زَوْجِ النَّبِىِّ صلى الله عليه وسلم إِنَّ الْعَبْدَ إِذَا اعْتَرَفَ بِذَنْبِهِ ثُمَّ تَابَ تَابَ اللَّهُ عَلَيْهِ (مسند أحمد. بيهقي)

Hadhrat Ayesha (RA) says that Rasulullah (Sallallahu Alaihi Wasallam) said, “When a slave admits his sins and then repents, Allah Ta’ala accepts his repentance” (Musnad Ahmad, Baihaqi)

How much kindness, generosity and beneficence is it that not only the sin of a person is forgiven because of repentance, but he becomes so pure and clean after it as if he has not committed any sin i.e., even the stain of that sin is washed away from his heart. A Hadith says:

عَبْدِ اللَّهِ مَسعُودٍ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم التَّائِبُ مِنَ الذَّنْبِ كَمَنْ لاَ ذَنْبَ لَهُ (رواه ابن ماجه و البيهقي في شعب الإيمان)

Hadhrat Abdullah bin Masood (RA) narrated that Rasulullah (Sallallahu Alaihi Wasallam) said, “A repentant from a sin is like the one who has not committed any sin”. (Ibn Majah, Baihaqi)

Different types of words have been narrated for repentance. The main purpose is to repent, so in whichever language anyone repents, it is correct. But, here it is worth to mention the invocation of repentance which has been declared as “Sayyidul Istigfaar” in the Hadith, and with it I end this topic.

سيد الاستغفار

عَنْ بُشَيْرِ بْنِ كَعْبٍ الْعَدَوِىِّ قَالَ حَدَّثَنِى شَدَّادُ بْنُ أَوْسٍ رضى الله عنه عَنِ النَّبِىِّ صلى الله عليه وسلم سَيِّدُ الاِسْتِغْفَارِ أَنْ تَقُولَ اللَّهُمَّ أَنْتَ رَبِّى ، لاَ إِلَهَ إِلاَّ أَنْتَ ، خَلَقْتَنِى وَأَنَا عَبْدُكَ ، وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ ، أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ ، أَبُوءُ لَكَ بِنِعْمَتِكَ عَلَىَّ وَأَبُوءُ بِذَنْبِى ، اغْفِرْ لِى ، فَإِنَّهُ لاَ يَغْفِرُ الذُّنُوبَ إِلاَّ أَنْتَ

Hadhrat Shaddad bin Aus (RA) narrated that Rasulullah (Sallallahu Alaihi Wasallam) said, “The superior ‘Istigfaar’ is that you say
أللهم أنت ربي up to إلا أنت (translation) O Allah! You are my Lord and there is no god but You; it is You Who created me. I am your slave and in agreement and promise with You in conformity to my strength; I take refuge in You from the evils I have done. I admit the blessing that you have showered on me and I admit my sin that I have committed. Forgive me, there is none else who can forgive than You”.

قَالَ وَمَنْ قَالَهَا مِنَ النَّهَارِ مُوقِنًا بِهَا ، فَمَاتَ مِنْ يَوْمِهِ قَبْلَ أَنْ يُمْسِىَ ، فَهُوَ مِنْ أَهْلِ الْجَنَّةِ ، وَمَنْ قَالَهَا مِنَ اللَّيْلِ وَهْوَ مُوقِنٌ بِهَا ، فَمَاتَ قَبْلَ أَنْ يُصْبِحَ ، فَهْوَ مِنْ أَهْلِ الْجَنَّةِ (بخاري)

"If somebody recites it during the day with firm faith in it, and dies on the same day before the evening, he will be among the dwellers of Paradise; and if somebody recites it at night with firm faith in it, and dies before the morning, he will be among the dwellers of Paradise." (Bukhari)