Musnad Ahmad 33:506

Hassan narrated to us, Ibn Lahi'ah narrated to us, Abu al-Zubayr narrated to us, from Jabir, who said: A man came to the Messenger of Allah, may Allah bless him and grant him peace, seeking food. The Messenger of Allah, may Allah bless him and grant him peace, gave him a wasq of barley. The man continued to eat from it, he and his wife and a servant of theirs, until they measured it. The Messenger of Allah, may Allah bless him and grant him peace, said: "Had you not measured it, you would have eaten from it, and it would have remained for you."