Musnad Ahmad 541:12

Abdullah ibn Yazid narrated to us, he said: Musa narrated to us, he said: I heard my father saying: I was with Amr ibn al-Aas in Alexandria, and they mentioned the state of living they were in. A man from the Companions said: "The Messenger of Allah, peace and blessings of Allah be upon him, passed away while his family had not eaten their fill of *ghalith* bread." Musa said: He means barley and *salt* (a type of grain) when they are mixed together.