Musnad Ahmad 33:144

Hushaym narrated to us, Abu al-Zubayr informed us, from Jabir, who said: We were with Abu Ubaydah. The Prophet, may Allah bless him and grant him peace, sent us with him on a journey, and our provisions ran out. We passed by a whale that the sea had cast up, and we wanted to eat from it, but Abu Ubaydah forbade us. Then, he said after that: "We are the messengers of the Messenger of Allah, may Allah bless him and grant him peace, and we are in the path of Allah, so eat." He said: So we ate from it for days. When we arrived, we mentioned that to the Messenger of Allah, may Allah bless him and grant him peace, and he said: "If any of it remains with you, then send some of it to us."