As a human being, we are impossible never did a mistake even prophet. The difference is a prophet has been forgiving the past and the future. So as common people we should pursue God’s forgiveness. Every day every time.
We can found many companions (Sahabah) have bad deeds and against Prophet Muhammad ﷺ on the past, such as Ikrimah bin Abu Jahl, Khalid bin Walid, Hindun binti Utbah etc. But after they convert to Islam, they do the best as Muslim they can.
There is a slave named Wahsyi bin Harb. He is the one who killed Prophet Muhammad’s Uncle – Hamzah. His master promised to him if he can killed Hamzah on the battle of Uhud, he will be free people. Wahsyi killed Hamzah Ra. with a spear. He was killed one of the best people. After Wahsyi converts to Islam and makes a Taubah (Repentance), he wants to pay off what he did before. During the time of Abu Bakr’s caliphate (after prophet Muhammad ﷺ passed away), show up the false prophet, Musailimah The Liar. Musailimah Al Kadzdzaab. Musailimah declaring ‘He is the prophet’. Musailimah and most of the Murtadin rebelling the Abu Bakr’ caliphate. The first army under Ikrimah bin Abu Jahl goes to against rebellion but no result. The second army under Khalid bin Walid sent to Yamamah. Wahsyi heard about this army wants to go to Yamamah so he joins to this army. This battle called as Battle of Yamamah. In the battlefield, Wahsyi succeeds to killed Musailimah The Liar by his spear liked he killed Hamzah in the battle of Uhud.
Sheikh Othman Al Khamees, one of the students Sheikh Utsaimin write down in his book ‘Kunuz As Siroh’. “Wahsyi bin Harb is So Amazing (Ajiib) after he converts to Islam and repents, by Taufiq Allah Tabaroka Wa Ta’ala until he killed Musailimah Al Kadzdzaab. He said: ‘I have killed Waliyullah (Hamzah) and I have killed Aduwallah (Musailimah)’ “.
Ari Abimanyu – The one seek God’s Mercy