The story of Abu Baseer
In Saheeh Bukhari it is reported that Allah’s Messenger (sallallahu alayhe wa sallam) made a peace treaty with the Quraysh, which allowed the Muslims to perform Umrah the year after the treaty was conducted. However, in this treaty there was a quite distressing condition, which said that if a Makkan embraced Islam and went to Allah’s Messenger to seek shelter, he would be handed back to the Makkans… After making this treaty, Allah’s Messenger (sallallahu alayhi wa sallam) returned to Madeenah. Now, a man named Abu Basir bin Asid Ath-Thaqafi from the Quraysh happened to have embraced Islam during this truce. When the Prophet returned to Medina, Abu Basir, the new Muslim convert from Quraish came to him. The infidels sent in his pursuit two men who said (to the Prophet), "Abide by the promise you gave us." So, the Prophet handed him over to them. They took him out (of the City) till they reached Dhul-Hulaifa where they dismounted to eat some dates they had with them. Abu Basir said to one of them, "By Allah, O so-and-so, I see you have a fine sword." The other drew it out (of the scabbard) and said, "By Allah, it is very fine and I have tried it many times." Abu Basir said, "Let me have a look at it."
When the other gave it to him, he hit him with it till he died, and his companion ran away till he came to Medina and entered the mosque running. When Allah's Apostle saw him he said, "This man appears to have been frightened." When he reached the Prophet he said, "My companion has been murdered and I would have been murdered too." Abu Basir came and said, "O Allah's Apostle, by Allah, Allah has made you fulfill your obligations by your returning me to them (i.e. the infidels), but Allah has saved me from them." The Prophet said, "Woe to his mother! What excellent war kindler he would be (i.e. he would start a war), should he only have supporters." When Abu Basir heard that, he understood that the Prophet would return him to them again, so he set off till he reached the seashore. Abu Jandal bin Suhail (another Muslim convert) got himself released from them (i.e. infidels) and joined Abu Basir. So, whenever a man from Quraysh embraced Islam he would follow Abu Basir till they formed a strong group. By Allah, whenever they heard about a caravan of Quraysh heading towards Sham, they stopped it and attacked and killed them (i.e. infidels) and took their properties. The people of Quraysh sent a message to the Prophet requesting him for the sake of Allah and kith and kin to send for (i.e. Abu Basir and his companions) promising that whoever (amongst them) came to the Prophet would be secure. So the Prophet sent for them (i.e. Abu Basir's companions).
{Saheeh Bukhari, Volume 3, Number 891}