Musnad Ahmad 31:93

Abu Mu’awiyah narrated to us, Al-A’mash narrated to us, from Abu Salih, from Abu Sa’id or from Abu Hurairah—Al-A’mash was in doubt—who said: When the Battle of Tabuk took place, the people were struck by famine. They said: "O Messenger of Allah, if you would permit us, we would slaughter our camels used for carrying water, so we could eat and use their fat." The Messenger of Allah, peace and blessings of Allah be upon him, said to them: "Do so." Then Umar came and said: "O Messenger of Allah, if they do that, the number of mounts will decrease. Instead, call them to bring the remnants of their provisions, then supplicate to Allah for blessing upon it; perhaps Allah will place [sufficiency] in that." The Messenger of Allah, peace and blessings of Allah be upon him, called for a leather mat and spread it out. Then he called them to bring the remnants of their provisions. A man would come with a handful of corn, another with a handful of dates, and another with a piece of bread, until a small amount of that had gathered on the mat. Then he supplicated for blessing upon it, and said to them: "Take [it] into your vessels." He said: So they took [it] into their vessels until they did not leave a single vessel in the camp without filling it. They ate until they were full, and there was some left over. Then the Messenger of Allah, 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 this, without doubting, but that Paradise will not be veiled from him."