It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that I saw the Prophet (peace and blessings be upon him) praying on a donkey, at that time he (peace be upon him) was going towards Khaybar, which is to the east.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5206
Hadith Gradingحکم دارالسلام:إسناده صحيح ، م : 700 .