Musnad Ahmad 1056
It was narrated that ‘Ali bin Rabee`ah said I rode behind ‘Ali (رضي الله عنه). When he put his foot in the stirrup, he said:
Bismillah (in the Name of Allah). When he got on his mount, he said: Al-Hamdu Lillah. `Glory be to the One Who has placed this (transport) at our service and we ourselves would not have been capable of that, and to our Lord is our final destiny` [Az-Zukhruf 43:13,14]. Abu Sa’eed, the freed slave of Banu Hashim, said: Then he said Al-Hamdu Lillah three times and Allahu Akbar three times, then he said Subhan Allah three times. Then he said: There is no god but You. Then he [the narrator] went back to the hadeeth of Wakee’ and said: Glory be to You, I have wronged myself, so forgive me; no one forgives sins but You. Then he smiled, and I said: What made you smile? He said: I was riding behind the Messenger of Allah     (ﷺ), and he did what you have seen me do, then he smiled and I said: What made you smile, O Messenger of Allah (ﷺ)? He said: `Allah, may He be blessed and exalted, says: How remarkable is My slave; He knows that no one forgives sin except Me.`
حَدَّثَنَا وَكِيعٌ، عَنْ إِسْرَائِيلَ، عَنْ أَبِي إِسْحَاقَ، عَنْ عَلِيِّ بْنِ رَبِيعَةَ، قَالَ كُنْتُ رِدْفَ عَلِيٍّ رَضِيَ اللَّهُ عَنْهُ فَلَمَّا وَضَعَ رِجْلَهُ فِي الرِّكَابِ قَالَ بِسْمِ اللَّهِ فَلَمَّا اسْتَوَى قَالَ الْحَمْدُ لِلَّهِ ‏{‏سُبْحَانَ الَّذِي سَخَّرَ لَنَا هَذَا وَمَا كُنَّا لَهُ مُقْرِنِينَ ‏.‏ وَإِنَّا إِلَى رَبِّنَا لَمُنْقَلِبُونَ‏}‏ وَقَالَ أَبُو سَعِيدٍ مَوْلَى بَنِي هَاشِمٍ ثُمَّ حَمِدَ اللَّهَ ثَلَاثًا وَاللَّهُ أَكْبَرُ ثَلَاثًا ثُمَّ قَالَ سُبْحَانَ اللَّهِ ثَلَاثًا ثُمَّ قَالَ لَا إِلَهَ إِلَّا أَنْتَ ثُمَّ رَجَعَ إِلَى حَدِيثِ وَكِيعٍ سُبْحَانَكَ إِنِّي ظَلَمْتُ نَفْسِي فَاغْفِرْ لِي إِنَّهُ لَا يَغْفِرُ الذُّنُوبَ إِلَّا أَنْتَ ثُمَّ ضَحِكَ قُلْتُ مَا يُضْحِكُكَ قَالَ كُنْتُ رِدْفًا لِرَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَفَعَلَ كَالَّذِي رَأَيْتَنِي فَعَلْتُ ثُمَّ ضَحِكَ قُلْتُ يَا رَسُولَ اللَّهِ مَا يُضْحِكُكَ قَالَ قَالَ اللَّهُ تَبَارَكَ وَتَعَالَى عَجَبٌ لِعَبْدِي يَعْلَمُ أَنَّهُ لَا يَغْفِرُ الذُّنُوبَ غَيْرِي‏.‏