Musnad Ahmad 33:624

Musa narrated to us, Ibn Lahi'ah narrated to us, from Abu al-Zubayr, from Jabir, from the Prophet, may God bless him and grant him peace, that a man came to him seeking food, so he fed him half 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 Prophet, may God bless him and grant him peace, said: "If you had not measured it, you would have eaten from it, and it would have remained for you."