Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Bukhari :: Book 5 :: Volume 59 :: Hadith 483
(The tree where the Ridwan Pledge of allegiance was taken by the Prophet) was mentioned before Said bin Al-Musaiyab. On that he smiled and said, "My father informed me (about it) and he had witnessed it (i.e. the Pledge) ."
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