Musannaf Ibn Abi Shayba 33:258

'Affan narrated to us, he said: Sulayman ibn al-Mughirah narrated to us, he said: Thabit said: Anas said: Barley became expensive, food became expensive in Medina during the time of Umar. So he began to eat barley, and his stomach found it disagreeable. He reached with his hand toward his stomach and said: "By Allah, it is nothing but what you see, until Allah expands [the provision] for the Muslims."