Musannaf Ibn Abi Shayba 3:5868

Abu Usama narrated to us, from Abdullah ibn Muhammad ibn Umar ibn Ali, from his father, from his grandfather: That Ali used to pray Maghrib while traveling, then eat dinner, then pray Isha immediately after it. Then he would say: "This is how I saw the Messenger of Allah, may Allah bless him and grant him peace, doing."