Pledge of the Tree
The Pledge of the Tree (Arabic: بيعة الشجرة bayʻat ash-shajarah) or Pledge of Satisfaction (Arabic: بيعة الرضوان bayʻat ar-riḍwān) or Pledge of Ridwan was a pledge that was sworn to the Islamic prophet Muhammad by his Sahaba (companions) prior to the Treaty of Hudaybiyyah (6 AH, 628 CE).
Bay’ah is promising to follow and obey. It did happen during the time of pervious prophets like when Easa Jesus (AS) asked people from Bani Israel : Who are my supporters? His disciples replied: We are the supporters of Allah (3:52). That was just an example of Bay’ah.