Narrated Tariq bin `Abdur-Rahman:
When I set out for Hajj, I passed by some people offering a prayer, I asked, "What is this mosque?" They said, "This is the Tree where Allah's Messenger (ﷺ) took the Ar-Ridwan Pledge of allegiance. Then I went to Sa`id bin Musaiyab and informed him about it. Sa`id said, "My father said that he was amongst those who had given the Pledge of allegiance to Allah's Messenger (ﷺ) beneath the Tree. He (i.e. my father) said, "When we set out the following year, we forgot the Tree and were unable to recognize it. "Then Sa`id said (perhaps ironically) "The companions of the Prophet (ﷺ) could not recognize it; nevertheless, you do recognize it; therefore you have a better knowledge."
Narrated Nafi`:
The people used to say that Ibn `Umar had embraced Islam before `Umar. This is not true. What happened is that `Umar sent `Abdullah to bring his horse from an Ansari man so as to fight on it. At that time the people were giving the Pledge of allegiance to Allah's Messenger (ﷺ) near the Tree, and `Umar was not aware of that. So `Abdullah (bin `Umar) gave the Pledge of Allegiance (to the Prophet) and went to take the horse and brought it to `Umar. While `Umar was putting on the armor to get ready for fighting, `Abdullah informed him that the people were giving the Pledge of allegiance to Allah's Apostle beneath the Tree. So `Umar set out and `Abdullah accompanied him till he gave the Pledge of allegiance to Allah's Messenger, and it was this event that made people say that Ibn `Umar had embraced Islam before `Umar.
Narrated Yazid:
I said to Salama, "For what did you give the Pledge of allegiance to the Prophet (ﷺ) on the Day of Hudaibiya?" He replied, "For death."
Narrated Yazid bin Abi Ubaid:
I said to Salama bin Al-Akwa`, "For what did you give the Pledge of allegiance to Allah's Messenger (ﷺ) on the day of Al-Hudaibiya?" He replied, "For death (in the Cause of Islam.).