Sayyiduna Abdullah (bin Mas'ud) (may Allah be pleased with him) says: "There is no verse of the Book of Allah except that I know where it was revealed and concerning whom it was revealed; and if I knew of anyone more knowledgeable than me about the Book of Allah, whom camels could reach, I would travel to him."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8399