Volume 9 · Book 90 · Hadith 350
Narrated Abu Huraira: Allah's Apostle said, "But for the emigration, I would have been one of the Ansar: and if the people took their way in a valley (or a mountain pass), I would take the Ansar's valley or the mountain pass."
— Sahih Bukhari, Volume 9, Book 90: Wishes, Hadith #350