Sahih al-Bukhari — Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) — Hadith No: 4164
Translation
Narrated Sa`id bin Al-Musaiyab:That his father was amongst those who had given the Pledge of allegiance (to the Prophet (ﷺ) ) beneath the Tree, and the next year when they went towards the Tree, they were not able to recognize it