Hamza bin Abid Al Mottalib, the uncle of the messenger of God (pbuh) was one of the courageous Arabs. He was known for his bravery. He was the one who insisted on muslims to get out of Al Madina and fight bani Quraysh out.
He was skilled in protecting God messenger (pbuh) from the harm of polytheists in dangerous moments and harsh conditions since the beginning of the Mohammadi call for Islam in Makkah.
He hardly responded to Abi Jahel who harmed the prophet (pbuh). He hit him in a way that cleaved his head in the presence of a group of Quraysh leaders, but no one had the courage to face him.
Hamza was a fighting muslim and a devoted commando hero in the sake of Islam. During the Badr battle, he killed “Sheeba” who is one of Quraysh heroes and courageous, and others. He only sought to support truth and morality and to recognize freedom in people and nations’ lives.
Hind bin Ataba, the wife of Abi Sofyan, hardly hated him. He decided to take revenge on the Muslims for her father, whatever the cost is.
So she commanded “Wahshi”, who was an Ethiopian servant for Jobayr bin Mot’im who killed his uncle during the Battle of Badr, to take revenge for her the way he could. She told her: if you kill Mohammad or Ali or Hamza, I’ll satisfy you with all your needs.
So Wahshi said: Regarding Mohammad, I can’t do it with him. Regarding Ali, I found him a careful man who pays much attention, and I do not lust for killing him. But regarding Hamza, I lust for killing him because when he’s angry he stops seeing in front of him.
Wahshi says: On the day of Uhud, I waylaid for Hamza at the root of a tree so that he approached me. Hamza’s sign at that time was of an ostrich feather in his chest. I looked at him damaging people with his sword, so I moved my bayonet (which he was skillful in). When I directed it towards him, I hit him with it. I injured him in his lower abdomen until the bayonet got out from between his legs. He tried to approach me but he couldn’t. I left him like this until he died. Then, I approached him to take my bayonet and went back to the tent and sat there. I had no benefits in killing someone else, I just killed him to be released from servitude.
When I came to Makkah, I was revealed from servitude. I remained there until God’s messenger (pbuh) entered Makkah so I ran to Al Ta’if and stayed there. When Al Ta’if delegation went to God messenger (pbuh) to embrace Islam, I was in trouble of doctrines, so I said: Should I go to Syria or Yemen, or other countries? I swear to God that I am in trouble. So a man told me: Woe unto you! He doesn’t kill anyone who embraces his religion or says his testimony of faith (testimony of Islam).
When he told me that, I went to the God’s messenger (pbuh) in Al Madina. I stood beside him and said the testimony of truth. When he saw me he said:” Aren’t you Wahshi?”.
I said:” Yes, O God’s messenger”.
He said:” Sit and tell me how you killed Hamza. I told him what happened to me. When I finished he said: Woe unto you! Go from here and don’t show me your face.
Yes, this is the greatest prophecy spirit, and this is the patience that God almighty has given to his prophet, the supreme islamic leader and the greatest teacher of humankind. He forgave the killer of his uncle despite the fact that he was able to kill him depending on much evidence and evidence!!
Wahshi says: I used to hide from God’s messenger (pbuh) not to let him see me, until he (pbuh) was dead.
When muslims went to fight Musaylima the liar, I went with him and took the bayonet that I killed Hamza with. When people met, I saw Musaylima holding his sword, so I prepared myself to kill him. A christian man also prepared himself to kill Musaylima. Both of us wanted to kill him. I prepared my bayonet, directed it towards him and hit him. The christian man also reached him and hit him with his sword.
This is what Wahshi has claimed. But Hisham said in his biography: I knew that Wahshi remained drinking wine until he took off from the Diwan (a place where muslims used to gather). Omar bin Al Khattab used to say that God wouldn’t leave the killer of Hamza. 
The Biography of the Master of Messengers (pbuh), Ayatollah Al Sheikh Jaafar Sobhani
 The Prophet’s Biography part 2 page 72-73.