The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fada'il Al-Sahabah)
Muslim :: Book 31 : Hadith 6177
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: If the din were at the Pleiades, even then a person from Persia would have taken hold of it, or one amongst the Persian descent would have surely found it.