Musannaf Ibn Abi Shayba 23:181

Affan narrated to us, he said: Hammad bin Salamah narrated to us, from Abu al-Zubayr, from Jabir, he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "I saw as if I were in a fortified coat of mail, and I saw a slaughtered cow. So I interpreted the coat of mail as Medina, and the cows as the cows of..."