Musnad Ahmad 25:1198

Abu al-Mughirah narrated to us, Abu Bakr ibn Abdullah narrated to us, from Ali ibn Abi Talhah, from Abdullah ibn Abbas: That the Messenger of Allah (ﷺ) let him ride behind him on his mount. When he was steady upon it, the Messenger of Allah (ﷺ) said "Allahu Akbar" (Allah is the Greatest) three times, praised Allah three times, glorified Allah three times, and declared the oneness of Allah once. Then he leaned back upon him and laughed. Then he turned to me and said: "There is no person who rides his mount and does as I have done, except that Allah, Blessed and Exalted is He, turns to him and laughs at him, just as I have laughed at you."