This hadlth has been narrated by Khalid al-Harith with the same chain of transmitters (with these words):

(The Prophet) was reciting Surat al-Fath as he was travelling on his mount.

وَحَدَّثَنَاهُ يَحْيَى بْنُ حَبِيبٍ الْحَارِثِيُّ، حَدَّثَنَا خَالِدُ بْنُ الْحَارِثِ، ح وَحَدَّثَنَا عُبَيْدُ، اللَّهِ بْنُ مُعَاذٍ حَدَّثَنَا أَبِي قَالاَ، حَدَّثَنَا شُعْبَةُ، بِهَذَا الإِسْنَادِ نَحْوَهُ وَفِي حَدِيثِ خَالِدِ بْنِ الْحَارِثِ قَالَ عَلَى رَاحِلَةٍ يَسِيرُ وَهُوَ يَقْرَأُ سُورَةَ الْفَتْحِ ‏.‏