My father was among those who pledged allegiance to the Prophet ﷺ under the tree, the Pledge of Ridwan. He said, "We set out the following year for the pilgrimage, but the location of that tree was hidden from us. If it has been made clear to you, then you know better than we do."
حدثنا عفان حدثنا أبو عوانة عن طارق
كان أبي ممن بايع النبي ﷺ تحت الشجرة بيعة الرضوان فقال انطلقنا في قابل حاجين فعمي علينا مكانها فإن كانت بينت لكم فأنتم أعلم
Its isnad is sahih. It appears in Bukhari, 7/447, no. 4113, in the book of military expeditions, the expedition of Hudaybiya.