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Allah's Messenger (ﷺ) said: "By Allah, I seek the forgiveness of Allah, and repent to Him more than seventy times in a day.
Reference:
Al-Bukhari, cf. Al-Asqalani, Fathul-Bari 11/101.
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Allah's Messenger (ﷺ) said: "O people, repent to Allah, for I verily repent to Him one hundred times a day.
Reference:
Muslim 4/2076.
Allah's Messenger (ﷺ) said: Whoever says:
Astaghfirullāha ‘l-'Aẓīm
alladhi lā ilāha illā huwa ‘l-ḥayyul-Qayyūm
wa atūbu ilayh.
Allah's Messenger (ﷺ) said: Whoever says:
I seek the forgiveness of Allah the Mighty, Whom there is none worthy of worship except Him, the Living, the Eternal,
and I repent to Him,
Allah will forgive him even if he has deserted the army's ranks.
Reference:
Abu Dawud 2/85, At-Tirmidhi 5/569, and Al-Hakim who declared it authentic
and Ath-Thahabi agreed with him 1/511. Al-Albani graded it authentic in
Sahih At-Tirmidhi 3/182. See also Jami'ul-'Usool li-'Ahdaith Ar-Rasool 4/
389-90 checked by Al-Arna'ut.
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Allah's Messenger (ﷺ) said: "The closest that the Lord comes to the slave is in the last portion of the night. So, if you are able to be among those who remember Allah in this hour, then be among them."
Reference:
At-Tirmidhi, An-Nasa'i 1/279 and Al-Hakim. See also Al-Albani, Sahih
At-Tirmidhi 3/183, and Jdmi'ul-'Usool with Al-Arna'ut's checking 4/144.
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Allah's Messenger (ﷺ) said: "The closest that the slave comes to his Lord is when he is prostrating, so invoke Allah much (in prostration)."
Reference:
Muslim 1/350.
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Allah's Messenger (ﷺ) said: "It is a heavy thing for my heart if I do not seek Allah's forgiveness a hundred times a day."
Reference:
Muslim 4/2075. Ibn 'Athir explains that the Prophet (ﷺ) was always
vigilant in his remembrance and drawing near to Allah, and if he forgot to
do any of what he normally did from time to time, or it slipped his mind,
he felt as if he had wronged himself and so he would begin to seek the
forgiveness of Allah. See Jami'ul-'Usool 4/386.