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.
Uhayrim was a mujahid of Islam from then on.
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.
Uhayrim gave the following answer, which made them happy:
"I came here because of my desire for Islam. I became a Muslim.
Uhayrim died a little while later and became a martyr.
Abu Hurayra said,"He is Amr bin Thabit."Then he narrated his story
Source:Siraat-e-Sahaba