Musnad Abu Ya'la al-Mawsili 2:91

Abu Hisham narrated to us, Ibn Fudayl narrated to us, Ibn Abi Ziyad narrated to us, from Asim ibn Ubayd Allah ibn Asim, from his father, from his grandfather Umar, who said: We were with the Prophet, peace and blessings of Allah be upon him, on a military expedition. We said, "O Messenger of Allah, the enemy has arrived, and they are full while the people are hungry." The Ansar said, "Shall we not slaughter our camels used for drawing water and feed them to the people?" The Prophet, peace and blessings of Allah be upon him, said, "Whoever has surplus food, let him bring it." So they began bringing a mudd, a sa', and more or less than that. The total of what was in the army was twenty-some sa's. The Prophet, peace and blessings of Allah be upon him, sat beside it and prayed for blessing. Then the Prophet, peace and blessings of Allah be upon him, said, "Take, and do not plunder." A man began taking into his leather bag and his sack, and they took into their containers until a man would tie the sleeve of his shirt and fill it. They emptied it, and the food remained as it was. Then the Prophet, peace and blessings of Allah be upon him, said, "I bear witness that there is no god but Allah and that I am the Messenger of Allah. No servant meets Allah with these two, having certainty, except that Allah will protect him from the heat of the Fire."