Musnad Abu Ya'la al-Mawsili 108:153

Abu Khaythama narrated to us, Jarir narrated to us, from Layth, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (peace and blessings of Allah be upon him) sent us, six hundred men, with Abu Ubaydah ibn al-Jarrah. We had nothing with us except a leather bag of dates. He said: We divided them among ourselves, and each man among us received five or seven dates. We ate them until hunger reached us. He said: We began to suck on their pits. When hunger reached us, we reached the seashore, and there was a whale like a massive sand dune, from which the water had receded. Some of us said: "Shall we eat this, while it is carrion?" Abu Ubaydah said: "You are warriors in the path of Allah, so eat; there is no harm in it." So we ate from it, salted some of it, and took some as provisions. When we reached the Messenger of Allah (peace and blessings of Allah be upon him), we mentioned that to him. He said: "There is no harm in it. Does any one of you have any of it with him to feed me?" He said: So some of us said to others: "Yes." And we sent some of it to him.