Narrated Abû Huraira radhiAllâhu `anhu: Allâh’s Apostle said, “Whoever says, ‘Subhan Allâh wa bihamdihi,’ one hundred times a day, will be forgiven all his sins even if they were as much as the foam of the sea.” [Sahîh Al-Bukhari]
Narrated Abû Huraira radhiAllâhu `anhu: Allâh’s Apostle sallAllâhu `alayhi wa sallam said, “Whoever says: ‘La ilaha illal-lah wahdahu la sharika lahu, lahu-l-mulk wa lahu-l-hamd wa huwa ‘ala kulli shai’in qadir,’ one hundred times will get the same reward as given for manumitting ten slaves; and one hundred good deeds will be written in his accounts, and one hundred sins will be deducted from his accounts, and it (his saying) will be a shield for him from Satan on that day till night, and nobody will be able to do a better deed except the one who does more than he.” [Sahîh Al-Bukhari]
Narrated Abû Hurayrah radhiAllâhu `anhu: Allâh’s Apostle sallAllâhu `alayhi wa sallam said: If anyone extols Allâh after every prayer thirty-three times [SubhanAllâh], and praises Allâh thirty-three times [Alhamdulillah], and declares His Greatness thirty-three times [Allâh hu Akbar], ninety-nine times in all, and say to complete a hundred: “There is no god but Allâh, having no partner with Him, to Him belongs sovereignty and to Him to praise due, and He is Potent over everything,” his sins will be forgiven even if these are as Abûndant as the foam of the sea. [Sahîh Muslim]
Abû Hurairah radhiAllâhu `anhu reported that the Prophet, sallAllâhu `alayhi wa sallam, said, “If anyone sits in an assembly where there is much clamor and says before getting up to leave, “Subhanaka Allâhumma wa bihamdika, ashadu an-la illaha illa-anta, astaghfiruka wa atubu ilayka” (Glory be to You, O Allâh, and I begin with declaring all praise is due to You, I testify that there is no god but You; I ask Your pardon and turn to You in repentance), he will be forgiven any sin that he might have committed while in that assembly. [Tirmidhi]
“If anyone says:
Astaghfirullah-alladhi la ilaha illa Huwal-Haiyul-Qayyoomu, wa atubu ilaihi
(I seek forgiveness of Allah besides Whom there is non worthy of worship, the Ever-Living, the Self-Subsisting, and I turn to Him in repentance)
his sins will be forgiven even if he should have run away from the battlefield.
In another narration, these words are to be repeated three times.
[Abu Dawud, At-Tirmidhi and Al-Hakim]
“The BEST SUPPLICATION FOR SEEKING FORGIVENESS (Syed-ul-Istighfar) is to say:
اللَّهُمَّ أَنْتَ رَبِّي لا إِلَهَ إِلا أَنْتَ خَلَقْتَنِي وَأَنَا عَبْدُكَ وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ أَبُوءُ لَكَ بِنِعْمَتِكَ عَلَيَّ وَأَبُوءُ لَكَ بِذَنْبِي فَاغْفِرْ لِي فَإِنَّهُ لا يَغْفِرُ الذُّنُوبَ إِلا أَنْ
Allahumma Anta Rabbi, la ilaha illa Anta, khalaqtani wa ana `abduka, wa ana `ala `ahdika wa wa`dika mastata`tu, a`udhu bika min sharri ma sana`tu, abu’u laka bini`matika `alayya, wa abu’u bidhanbi faghfir li, fa innahu la yaghfirudh-dhunuba illa Anta
(O Allah! You are my Rubb. There is no true god except You. You have created me, and I am Your slave, and I hold to Your Covenant as far as I can. I seek refuge in You from the evil of what I have done. I acknowledge the favours that You have bestowed upon me, and I confess my sins. Pardon me, for none but You has the power to pardon).
He who supplicates in these terms during the day with firm belief in it and dies on the same day (before the evening),
he will be one of the dwellers of Jannah; and if anyone supplicates in these terms during the night with firm belief in it and dies before the morning, he will be one of the dwellers of Jannah.”