Umayr ibn Wahb
Since he had persecuted Muslims earlier, he feared the well-being of his son, especially since he remembered the many Meccans killed in Badr. He then conspired with Safwan ibn Umayyah to kill Muhammad. Safwan agreed to take all of Umayr's debts in order for Umayr to go to the Muslims and kill Muhammad.
When he got there, he was recognized by Umar ibn al-Khattab, who said:
This is the dog, the enemy of God, Umayr ibn Wahb. By God, he has only come to do evil. He led the Polytheists (Arabic: Mushrikeen) against us in Mecca and he was a spy for them against us shortly before [the Battle of] Badr. Go to the Messenger of God, stand around him and warn him that this dirty traitor is after him.
Umayr was arrested and brought to Muhammad, who gave him a warm welcome and asked for his motives. He replied that he wanted the Badr captives to be released. Muhammad inquired about the sword that Umayr brought with him, and then retold for Umayr the exact events that led him there, including his secret conversation with Safwan ibn Umayyah. Umayr was so awe-struck that he immediately said his shahada, hence becoming a Muslim. Muhammad then said to his companions, "Instruct your brother in his religion. Teach him the Qur'an and set free his prisoner [Wahb ibn Umayr]."
Later, at the Conquest of Mecca, he helped Safwan ibn Umayyah obtain amnesty, resulting in his also becoming a Muslim.
- A section from Companions of the Prophet, by Abdul Wahid Hamid