Musannaf Ibn Abi Shayba 22:194

Yazid ibn Harun narrated to us, he said: Humayd informed us, from Anas, that Umar said upon the pulpit: "And fruits and fodder (wa fakihatan wa abba)." Then he said: "This fruit, we have known it, but what is the fodder (al-abb)?" Then he returned to himself and said: "Indeed, this is truly affectation, O Umar."