Musnad Ahmad 32:908

Waki’ and Ibn Ja’far narrated to us, they said: Shu’bah narrated to us, from Qatadah, from Anas, who said: There was a panic in Medina, so the Prophet, peace and blessings of Allah be upon him, borrowed a horse belonging to Abu Talhah called Mandub. He rode it, then he came back and said: "We did not see any panic, and we found it to be a sea."