Amr bin Thabit Uhayrim (r.a.)
Amr bin Thabit was known by the nickname “Uhayrim”. Amr was from Madinah. Although all members of his tribe became Muslims, he continued to oppose the Muslims on his own.
During the Battle of Uhud, Uhayrim, who remained in Madinah, started to think. What was the reason for the Muslims to work so hard for the cause they believed in and not to avoid any sacrifices? Uhayrim was thinking about it and as he thought, the light of belief started to illuminate his heart and face. Finally, he decided to become a Muslim. He uttered kalima ash-shahada.
Uhayrim was a mujahid of Islam from then on. It was impossible for him to remain in Madinah comfortably while his religious brothers fought against the ferocious polytheists and shed their blood. He girded himself with a sword and proceeded to Uhud. He arrived at Uhud at the most violent moment of the war. He fought heroically. Finally, he was severely injured and fell down.
The war was over. The Muslims had many martyrs. Those who were strong enough to walk wandered among the martyrs, trying to help the wounded. Meanwhile, they saw Uhayrim, who was about to breathe his last breath. They were very surprised because they knew him as a polytheist. Some of them even thought that he was there to help the polytheists. They approached him to find out and asked him, "O Amr! Why did you come here? Did you want to help your tribe or to help Islam?"
Uhayrim gave the following answer, which made them happy:
"I came here because of my desire for Islam. I became a Muslim. I believed in Allah and His Messenger. Then I took my sword and came here to fight against the polytheists in the way of Allah and His Messenger."
Uhayrim died a little while later and became a martyr.
The Companions informed the Messenger of Allah about him. The Prophet said, "He is a person of Paradise. He did very few things but he received a lot of rewards."
It was years after this incident. Hz. Abu Hurayra asked the people around him, "Who is the person who never performed a prayer but is a person of Paradise?" They kept silent; they could not answer. Abu Hurayra said, "He is Amr bin Thabit." Then he narrated his story. 
Usdul-Ghaba, 4: 90-91; Isaba, 2: 526-527.