Istighfar

Istighfar (Arabic: استغفار‎ istiġfār), also Astaghfirullah (Arabic: أستغفر الله‎ ʾastaġfiru l-lāh) is the act of seeking forgiveness from Allah. This act is generally done by repeating the Arabic words astaghfirullah, meaning "I seek forgiveness from Allah". It is considered one of the essential parts of worship in Islam.

A Muslim will use this phrase often, even in conversation with another person. When a Muslim abstains from doing wrong (such as experiencing envy, jealousy, pride, and haughtiness) or even wishes to prove their innocence in an incident, they will use this expression. After every salat (prayer), a Muslim will typically recite the phrase three or more times. Arabic-speaking non-Muslims such as Arab Christians sometimes also employ the phrase.

Invocations For Forgiveness

• Arabic: رَبَّنَا إِنَّنَا آمَنَّا فَاغْفِرْ لَنَا ذُنُوبَنَا وَقِنَا عَذَابَ النَّارِ‎

Our Lord! we have indeed believed: forgive us, then, our sins, and save us from the agony of the Fire

— Quran, sura 3 (Al Imran), ayat 16^[1]

• Arabic: سُبْحَانَكَ تُبْتُ إِلَيْكَ وَأَنَا أَوَّلُ الْمُؤْمِنِينَ‎

Glory be to Thee! To Thee I turn in repentance, and I am the first to believe

— Quran, sura 7 (Al-A'raf), ayat 143^[2]

• Arabic: اللَّهُمَّ إنِّي أسْألُكَ يَا اللَّهُ بِأنَّكَ الْوَاحِدُ الأحَدُ الصَّمَدُ الَّذِي لَمْ يَلِدْ وَ لَمْ يُولَدْ وَلَمْ يَكُنْ لَهُ كُفُواً أحَدٌ، أنْ تَغْفِرَ لِي ذُنُوبِي إنَّكَ أنْتَ الْغَفُورُ الَّرحِيمُ‎ Allāhumma inn-ī ʾasʾalu-ka yā llāhu bi-ʾanna-ka l-Wāḥidu l-ʾAḥadu ṣ-Ṣamadu l-laḏī lam yalid wa-lam yūlad wa-lam yakun la-hu kufuwan ʾaḥadun, an taghfira lī ḏunūb-ī ʾinna-ka ʾAnta l-Ġafūru r-Raḥīmu O Allah! I ask You, O Allah, You are the One, the Only, Self Sufficient Master, who was not begotten and begets not and none is equal to Him. Forgive me my sins, surely you are Forgiving, Merciful.

  — Sunan an-Nasa'i, The Book of Forgetfulness in Prayer, Hadis no.123 ^[3]

• Arabic: اللهم اغفر لي، وارحمني، واهدني، وعافني، وارزقني‎ Allāhumma ġfir lī, wa-rḥam-nī, wa-hdi-nī, wa ʿāfi-nī, wa-rzuq-nī O Allah! Forgive me, have mercy on me, guide me, guard me against harm and provide me with sustenance and salvation.

  — Riyadh as-Saaliheen, The Book of Du'a (Supplications), Hadis no.5 ^[4]

Sayyidul-Istighfar (The Chief Prayer for Repentance)

Reported on the authority of Shaddad ibn aws, Muhammad (صلى الله عليه وسلم) said “Sayyidul-Istighfar is:

اللَّهُمَّ أَنْتَ رَبِّي لّا إِلَهَ إِلَّا أَنْتَ، خَلَقْتَنِي وَأَنَا عَبْدُكَ، وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ، أَعُوذُ بِكَ مِنْ شَرٍّ مَا صَنَعْتُ، أَبُوءُ لَكَ بِنِعْمَتِكَ عَلَيَّ، وَأَبُوءُ بِذَنْبِي فَاغْفِر لِي فَإِنَّهُ لَا يَغْفِرُ الذُّنُوبَ إِلَّا أَنْتَ

Allahumma anta rabbee la ilaha illa anta, (O Allah, You are my Lord, none has the right to be worshiped except You,) khalaqtanee wa-ana ‘abduka, (You created me and I am Your servant) wa-ana ‘alaa ‘ahdika wawa’dika mas-tata’tu, (and I abide to Your covenant and promise [to honor it] as best I can,) a’oothu bika min sharri ma sana’tu, (I take refuge in You from the evil of which I committed) aboo-o laka bini’matika ‘alaya, (I acknowledge Your favor upon me) wa-aboo-o bizambee, faghfir lee (and I acknowledge my sin, so forgive me,) fa-innahu la yaghfiruz-zunooba illa ant. (for verily none can forgive sins except You.)

Then Prophet Muhammad (May Allah be pleased with him) continued "If person recites this during the day with strong faith in it and dies on the same day before the sunset, he will be among the people of Paradise and if somebody recites it at night with strong faith in it and dies before sunrise he will be among the people of Paradise."

References

1. Quran 3:16
2. Quran 7:143
3. http://sunnah.com/nasai/13#123
4. http://sunnah.com/riyadussaliheen/17/5