Ibn 'Umar's father ('Umar) sent (him i.e. 'Abdullâh) to bring his horse from an man. At that time the people were giving the Bai'a (pledge) to Allâh's Messenger (ﷺ) near the tree, and 'Umar was not aware of that. So 'Abdullâh (bin Umar) gave the Bai'a (pledge) (to the Prophet ﷺ) and went to take the horse and brought it to Umar. While Umar was putting on the armour to get ready for fighting, 'Abdullâh informed him that the people were giving the Bai'a (pledge) to Allâh's Messenger (ﷺ) beneath the tree. So 'Umar set out and Abdullâh accompanied him till he gave the Bai'a (pledge) to Allâh's Messenger (ﷺ) and it was this ' event that made people say that Ibn 'Umar had embraced Islâm (or given the Hudaibîya Pledge) before 'Umar. [5:500-O.B]