Musnad Ahmad 753
It was narrated that `Ali bin Rabee`ah said:
I saw ‘Ali (رضي الله عنه) when a mount was brought to him to ride. When he put his foot in the stirrup, he said: Bismillah (in the Name of Allah). When he got on it, he said: 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. Then he said Alhamdulillah three times and Allahu Akbar three times, then he said: Glory be to You, there is no god but You. I have indeed wronged myself, so forgive me. Then he smiled, and I said: Why are you smiting, O Ameer al-Mu`mimeen? He said: I saw the Messenger of Allah (ﷺ) do what I have done, then he smiled and I said: Why are you smiling O Messenger of Allah (ﷺ) He said: `The Lord marvels at His slave when he says, `Lord forgive me,` and He says: `My slave knows that no one forgives sins but Me.`
حَدَّثَنَا يَزِيدُ، أَنْبَأَنَا شَرِيكُ بْنُ عَبْدِ اللَّهِ، عَنْ أَبِي إِسْحَاقَ، عَنْ عَلِيِّ بْنِ رَبِيعَةَ، قَالَ رَأَيْتُ عَلِيًّا رَضِيَ اللَّهُ عَنْهُ أُتِيَ بِدَابَّةٍ لِيَرْكَبَهَا فَلَمَّا وَضَعَ رِجْلَهُ فِي الرِّكَابِ قَالَ بِسْمِ اللَّهِ فَلَمَّا اسْتَوَى عَلَيْهَا قَالَ الْحَمْدُ لِلَّهِ ‏{‏سُبْحَانَ الَّذِي سَخَّرَ لَنَا هَذَا وَمَا كُنَّا لَهُ مُقْرِنِينَ ‏.‏ وَإِنَّا إِلَى رَبِّنَا لَمُنْقَلِبُونَ‏}‏ ثُمَّ حَمِدَ اللَّهَ ثَلَاثًا وَكَبَّرَ ثَلَاثًا ثُمَّ قَالَ سُبْحَانَكَ لَا إِلَهَ إِلَّا أَنْتَ قَدْ ظَلَمْتُ نَفْسِي فَاغْفِرْ لِي ثُمَّ ضَحِكَ فَقُلْتُ مِمَّ ضَحِكْتَ يَا أَمِيرَ الْمُؤْمِنِينَ قَالَ رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَعَلَ مِثْلَ مَا فَعَلْتُ ثُمَّ ضَحِكَ فَقُلْتُ مِمَّ ضَحِكْتَ يَا رَسُولَ اللَّهِ قَالَ يَعْجَبُ الرَّبُّ مِنْ عَبْدِهِ إِذَا قَالَ رَبِّ اغْفِرْ لِي وَيَقُولُ عَلِمَ عَبْدِي أَنَّهُ لَا يَغْفِرُ الذُّنُوبَ غَيْرِي‏.‏