Shortening the Prayer

Malik :: Book 9 : Hadith 9.7.27

Yahya related to me from Malik from Amr ibn Yahya al-Mazini from Abu'l-Hubab Said ibn Yasar that Abdullah ibn Umar said, "I saw the Messenger of Allah, may Allah bless him and grant him peace, praying on a donkey while heading towards Khaybar."