Musnad Ahmad 33:203

Sufyan narrated to us, hearing Amr, Jabir saying: "The Messenger of Allah (ﷺ) sent us out in a group of three hundred riders, with Abu Ubaydah ibn al-Jarrah as our commander. We stayed on the coast until our provisions ran out, to the point that we ate the *khabt* (leaves of trees). Then, the sea cast out a creature called 'al-Anbar' (the ambergris/whale). We ate from it for half a month until our bodies were restored. Abu Ubaydah took one of its ribs and set it upright. He looked at the tallest camel, and it passed underneath it. There was a man who would slaughter three camels, then three camels, then three camels, but Abu Ubaydah forbade him."