On the authority of our master Abdullah ibn Abbas (may Allah be pleased with them both), who said: While we were with the Messenger of Allah ﷺ, Ali ibn Abi Talib came to him and said: "May my father and mother be sacrificed for you — this Quran slips away from my chest, and I find myself unable to retain it." The Messenger of Allah ﷺ said to him: "O Abu al-Hasan, shall I not teach you words by which Allah will benefit you and those to whom you teach them, and make what you have learned remain firm in your chest?" He said: "Yes, O Messenger of Allah, teach me." He said: "When the night before Friday comes, if you are able, stand (in prayer) in the last third of the night [in the pre-dawn hours of Friday], for it is an hour witnessed (by the angels), and supplication in it is answered — and my brother Yaqub (Jacob) said to his sons: 'I will (in due time) ask forgiveness for you from my Lord' (Yusuf: 98), meaning: [he delayed it] until Friday [before dawn]. If you cannot, then stand in the middle of [the night]. If you cannot, then stand at the beginning of the night (Thursday night). Pray four rak'ahs. In the first, recite al-Fatihah and Surah Ya-Sin. In the second, al-Fatihah and Ha-Mim ad-Dukhan. In the third, al-Fatihah and Alif-Lam-Mim as-Sajdah. In the fourth, al-Fatihah and Tabarak (al-Mulk). When you finish the tashahhud, praise Allah and give beautiful thanks to Him, send blessings upon me and do so beautifully, and upon all the Prophets, and seek forgiveness for the believing men and women and for your brothers who preceded you in faith. Then say at the end of that: O Allah, have mercy on me by enabling me to abandon sins forever as long as You keep me alive, and have mercy on me by sparing me from burdening myself with what does not concern me, and grant me a discerning eye for what pleases You. O Allah, Originator of the heavens and the earth, Possessor of majesty, generosity, and irresistible might — I ask You, O Allah, O Most Merciful, by Your majesty and the light of Your Countenance, to make my heart cling to the memorization of Your Book as You have taught me, and enable me to recite it in the manner that earns me Your good pleasure. O Allah, Originator of the heavens and the earth, Possessor of majesty, generosity, and irresistible might — I ask You, O Allah, O Most Merciful, by Your majesty and the light of Your Countenance, to illuminate my sight through Your Book, to make my tongue fluent with it, to relieve my heart through it, to open my chest through it, and to cleanse my body through it. For none helps me upon the truth other than You, and none can grant it but You, and there is no power nor strength except with Allah, the Most High, the Most Great. O Abu al-Hasan, do this for three Fridays, or five, or seven — and you will be answered by Allah's permission. By the One who sent me with the truth, it never fails a believer." Abdullah ibn Abbas said: "By Allah, Ali did not wait long—five or seven (Fridays)—before he came to the Messenger of Allah ﷺ in a similar gathering and said: 'O Messenger of Allah, before, I could only retain about four verses, and when I would recite them to myself, they would slip away. But now I learn forty verses or so, and when I recite them to myself, it is as though the Book of Allah is before my very eyes. I used to hear a hadith, and when I tried to repeat it, it would slip away. But now I hear hadiths and when I relate them, I don't miss a single letter.'" The Messenger of Allah ﷺ then said to him: "A believer, by the Lord of the Ka'bah, O Abu al-Hasan!" --- (Narrated by al-Tirmidhi, and similarly by al-Hakim in al-Mustadrak and al-Diya' al-Maqdisi in al-Mukhtarah.