Istighfar is a short phrase that means seeking forgiveness from Allah SWT for the sins that have been committed. Istighfar comes from the Arabic word "استغفار" (istaghfār), which is derived from the root word "غفر" (ghafara) meaning "to cover" or "to forgive". Istighfar is one form of worship and is recommended to be practiced regularly. Reading istighfar signifies human acknowledgment of their weaknesses and sins in the presence of Allah SWT. This is a sign of awareness of human limitations and dependence on Allah. Istighfar is also considered as one of the ways to draw closer to Allah and obtain His forgiveness.

When you want to sleep, it is better to recite the istighfar sentence below three times: أَسْتَغْفِرُ اللَّهَ الْعَظِيمَ الَّذِي لَا إِلَهَ إِلَّا هُوَ الْحَيُّ الْقَيُّومُ وَأَتُوبُ إِلَيْهِ Astaghfirullahal 'azhiim, alladzii laa ilaaha illaa huwalhayyul-qayyuum, wa atuubu ilaiih. Meaning: "I seek forgiveness from Allah, the Almighty, there is no god but Him, the Ever-Living, the Sustainer of all existence, and I repent to Him."

Sheikh Muhammad bin Abu Bakar Ushfury in the book Al-Mawa'izh Al-Usfuriyah quoted from the companion Abu Sa'id Al-Khudri may Allah be pleased with him, the Prophet SAW said: "Whoever recites three times before going to sleep: Astaghfirullaahal-'Azhiim, Alladzii Laa Ilaaha Illaa Huwalhayyul-Qayyuum, wa Atuubu Ilaiih, then Allah forgives his sins even if they are as numerous as the foam in the ocean, as numerous as the leaves of trees, as numerous as the grains of soft sand, and as numerous as the days of the world."

Muhammad bin Sa'id bin Muhammad said, "I heard Abu Sahl Al-Bukhari, who was the muezzin at Masjid Bani Ma'ruf in the city of Bukhoro, a pious person, saying: I saw the Prophet Muhammad (SAW) in a dream and I saw someone saying, 'This is the companion Abu Bakar on the right side of the Prophet, and the companion Umar bin Khattab on the left side of the Prophet.' Then I came before the Prophet Muhammad (SAW), he shook hands with me, then Abu Bakar shook hands with me, and then Umar shook hands with me."

I asked, "O Messenger of Allah, Abu Mu'awiyah has narrated to us, from Abdullah bin Al-Walid, from Athiyyah, from Sahabat Abu Said Al-Khudri who said, 'Whoever wants to sleep while reciting three times: أَسْتَغْفِرُ اللَّهَ الْعَظِيمَ الَّذِي لَا إِلَهَ إِلَّا هُوَ الْحَيُّ الْقَيُّومُ وَأَتُوبُ إِلَيْهِ' (Astaghfirullahal-Adzimal-ladzi la ilaha illa huwal-hayyul-qayyum wa atubu ilaih), then Allah will forgive his sins even if they are as abundant as the foam of the sea, as numerous as the grains of soft sand, as plentiful as the leaves of trees, and as numerous as the days in the world.' I thought it was also said, 'Even if the sins are as numerous as the drops of rain.' Then I asked the Messenger of Allah (SAW), 'Is this Hadith from you, O Messenger of Allah?' He nodded his head in affirmation."