Musannaf Ibn Abi Shayba 4:107

Abu Dawud Umar ibn Sa'd narrated to us, from Sufyan, from al-Awza'i, from Yahya ibn Abi Kathir, from Abu Salamah, from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) was on a journey, and with him were Abu Bakr and Umar. Food was brought to him, so he said to them both, "Draw near and eat." They said, "O Messenger of Allah, we are fasting." He said, "Prepare to depart with your companion, work with your companion, draw near and eat."