Narrated Anas bin Malik: Allah's Apostle (salallahu 'alaihi wassalam) arrived at Medina with Abu Bakr, riding behind him on the same camel. Abu Bakr was an elderly man known to the people, while Allah's Apostle (salallahu 'alaihi wassalam) was a youth that was unknown. Thus, if a man met Abu Bakr, he would say, "O Abu Bakr! Who is this man in front of you?" Abu Bakr would say, "This man shows me the Way," One would think that Abu Bakr meant the road, while in fact, Abu Bakr meant the way of virtue and good. Then Abu Bakr looked behind and saw a horse-rider persuing them. He said, "O Allah's Apostle (salallahu 'alaihi wassalam)! This is a horse-rider persuing us." The Prophet looked behind and said, "O Allah! Cause him to fall down." So the horse threw him down and got up neighing. After that the rider, Suraqa said, "O Allah's Prophet (salallahu 'alaihi wassalam)! Order me whatever you want." The Prophet said, "Stay where you are and do not allow anybody to reach us." So, in the first part of the day Suraqa was an enemy of Allah's Prophet and in the last part of it, he was a protector [Hadith from Sahih Bukhari, Volume 5, Book 58: Merits of Helpers in Medina (Ansaar), Hadith Number 250].