Jami` at-Tirmidhi, Volume 6, Book 46, Hadith 3563 (DarusSalam) ⓘ
Ali [may Allah be pleased with him] narrated: that a Mukatib came to him and said: “Indeed I am not capable of my Kitabah so aid me.” He said: “Should I not teach you words that the Messenger of Allah taught me? If you had a debt upon you similar to the mountain of Sir, Allah would fulfill it for you. He said: ‘Say: O Allah, suffice me with Your lawful against Your prohibited, and make me independent of all those besides You (Allāhummakfinī biḥalālika `an ḥarāmika, wa aghninī bi faḍlika `amman siwāka).’”
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ عَبْدِ الرَّحْمَنِ، أَخْبَرَنَا يَحْيَى بْنُ حَسَّانَ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ إِسْحَاقَ، عَنْ سَيَّارٍ، عَنْ أَبِي وَائِلٍ، عَنْ عَلِيٍّ، رضى الله عنه أَنَّ مُكَاتَبًا، جَاءَهُ فَقَالَ إِنِّي قَدْ عَجَزْتُ عَنْ كِتَابَتِي فَأَعِنِّي . قَالَ أَلاَ أُعَلِّمُكَ كَلِمَاتٍ عَلَّمَنِيهِنَّ رَسُولُ اللَّهِ صلى الله عليه وسلم لَوْ كَانَ عَلَيْكَ مِثْلُ جَبَلِ صِيرٍ دَيْنًا أَدَّاهُ اللَّهُ عَنْكَ قَالَ " قُلِ اللَّهُمَّ اكْفِنِي بِحَلاَلِكَ عَنْ حَرَامِكَ وَأَغْنِنِي بِفَضْلِكَ عَمَّنْ سِوَاكَ " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ .
also referenced under: Hadith 3563 (Reference) & Book 48, Hadith 194 (In-Book)