It is reported about Sayyiduna Ali (may Allah be pleased with him) that he was asked: May a man ride his sacrificial animal? He replied: There is no harm in it. The Prophet (peace and blessings be upon him) passed by some men who were walking, and the Prophet (peace and blessings be upon him) ordered them to ride the sacrificial animal of the Prophet (peace and blessings be upon him). Sayyiduna Ali (may Allah be pleased with him) said: You will not follow anything more virtuous than the Sunnah of your Prophet (peace and blessings be upon him).
Ahmad recorded it. Its chain contains a narrator, Muhammad bin Ubaydullah bin Abi Rafi', whom Ibn Hibban declared "thiqah" (trustworthy), while a group (of scholars) declared him da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحج / 5396