A longer variant is ʾastaġfiru -llāha rabbī wa-ʾatūbu ʾilayhi (Arabic: أَسْتَغْفِرُ ٱللَّٰهَ رَبِّي وَأَتُوبُ إِلَيْهِ) which means “Verily, I seek the forgiveness of God, who is my Lord and Sustainer, and I turn to Him in repentance”. It is considered one of the essential parts of worship in Islam.
The virtue of Astaghfar | Astaghfirullah | Seeking Forgiveness
Astaghfirullah is the simple but very important powerful Dua. Astaghfar is expressing that remorse and cry for the forgiveness of Allah. Astaghfar is the keyword to changing the destination from hell to heaven. So it is super protection from the devil and a way to get to the vicinity of the almighty Allah. Repentance [Tawbah] and Istighfar is the most meritorious acts for the Muslims. It is a simple but powerful supplication. Seeking forgiveness of Allah 100 times a day is Sunnah of beloved Prophet Muhammad (ﷺ). Tawbah is not only necessary for seeking the shelter of sin but it is also the thankfulness of Allah for his immense favour to us. As we realize the greatness of Allah, Most High, our efforts of obedience clearly are seen to be Inadequate. But a person higher on the scale of taqwa and do more Astsghfar consequently get the mercy of Allah.
Dua for Astaghfar