Short answer
Istighfar (asking Allah's forgiveness) wipes away sins, protects from punishment, and in the Quran is linked to rain, wealth, children and strength. The Prophet ﷺ, though forgiven, sought forgiveness more than seventy, even a hundred, times a day. It is sunnah to make it a daily habit.
Istighfar is mustahabb at all times and wajib as part of repentance after a sin. Simple wording such as astaghfirullah is enough, and Sayyid al-Istighfar is the best form.
The four schools agree on this.
Explanation
Benefits named in the Quran:
- Forgiveness: those who remember Allah after a sin and ask forgiveness are forgiven (3:135). Allah forgives all sins for the one who repents (39:53).
- Rain, wealth and children: Nuh told his people that if they asked forgiveness, Allah would send rain, increase them in wealth and children, and give them gardens and rivers (71:10 to 12).
- Good provision in this life: seek forgiveness and repent, and He will let you enjoy a good provision (11:3).
- Protection from punishment: Allah would not punish them while they seek forgiveness (8:33).
From the sunnah. The Prophet ﷺ said he sought Allah's forgiveness and repented more than seventy times a day, and in another narration a hundred times. He taught Sayyid al-Istighfar, the master of seeking forgiveness, and said that if you did not sin, Allah would bring people who sin and then seek forgiveness so that He forgives them. Istighfar is not only for big sins; it polishes the heart and keeps you humble.
How to make it a habit:
- Say astaghfirullah three times after every fard salah.
- Read Sayyid al-Istighfar morning and evening.
- Say astaghfirullah wa atubu ilayh a hundred times a day, using a tasbih counter if it helps.
- Seek forgiveness in the last part of the night, praised in the Quran (3:17).
A popular report that whoever holds fast to istighfar will be given a way out of every worry has a weak chain, though its meaning matches the ayat above. For repenting from a specific sin, see how to repent in Islam and duas for forgiveness.
The evidence
Quran, Surah Nooh 71:10-12
فَقُلْتُ ٱسْتَغْفِرُوا۟ رَبَّكُمْ إِنَّهُۥ كَانَ غَفَّارًۭا ﴿١٠﴾ يُرْسِلِ ٱلسَّمَآءَ عَلَيْكُم مِّدْرَارًۭا ﴿١١﴾ وَيُمْدِدْكُم بِأَمْوَٰلٍۢ وَبَنِينَ وَيَجْعَل لَّكُمْ جَنَّٰتٍۢ وَيَجْعَل لَّكُمْ أَنْهَٰرًۭا ﴿١٢﴾
And said, 'Ask forgiveness of your Lord. Indeed, He is ever a Perpetual Forgiver. He will send [rain from] the sky upon you in [continuing] showers And give you increase in wealth and children and provide for you gardens and provide for you rivers.
Istighfar brings rain, wealth and children.
Quran, Surah Hud 11:3
وَأَنِ ٱسْتَغْفِرُوا۟ رَبَّكُمْ ثُمَّ تُوبُوٓا۟ إِلَيْهِ يُمَتِّعْكُم مَّتَٰعًا حَسَنًا إِلَىٰٓ أَجَلٍۢ مُّسَمًّۭى وَيُؤْتِ كُلَّ ذِى فَضْلٍۢ فَضْلَهُۥ ۖ وَإِن تَوَلَّوْا۟ فَإِنِّىٓ أَخَافُ عَلَيْكُمْ عَذَابَ يَوْمٍۢ كَبِيرٍ ﴿٣﴾
And [saying], "Seek forgiveness of your Lord and repent to Him, [and] He will let you enjoy a good provision for a specified term and give every doer of favor his favor. But if you turn away, then indeed, I fear for you the punishment of a great Day.
Istighfar brings good provision.
Quran, Surah Al-Anfaal 8:33
وَمَا كَانَ ٱللَّهُ لِيُعَذِّبَهُمْ وَأَنتَ فِيهِمْ ۚ وَمَا كَانَ ٱللَّهُ مُعَذِّبَهُمْ وَهُمْ يَسْتَغْفِرُونَ ﴿٣٣﴾
But Allah would not punish them while you, [O Muhammad], are among them, and Allah would not punish them while they seek forgiveness.
Istighfar protects from punishment.
Sahih al-Bukhari 6307
Sahih... والله إني لأستغفر الله وأتوب إليه في اليوم أكثر من سبعين مرة ...
"By Allah, I seek Allah's forgiveness and repent to Him more than seventy times a day."
The Prophet's ﷺ own daily istighfar.
Sahih Muslim 2749
Sahih... لو لم تذنبوا لذهب الله بكم ولجاء بقوم يذنبون فيستغفرون ...
"If you did not sin, Allah would take you away and bring people who sin and then seek forgiveness."
Allah loves the servant who returns to Him.
Where the ruling is recorded
- al-Adhkar (al-Nawawi), Chapter on istighfar. Collects the wordings and virtues of seeking forgiveness.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.