Did Prophet Mohammed (PBUH) take part in the actual fighting in the different battles, and did he (PBUH) ever kill anyone?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The Prophet, sallallaahu ‘alayhi wa sallam, fought the enemies of Allaah The Almighty with his own hands and he participated in the battlefield; rather, he was the nearest person to the enemy. ‘Ali narrated, “When the battle was at its peak, and we were face to face with the enemy, we used to shield ourselves behind the Prophet, sallallaahu ‘alayhi wa sallam, as he was the nearest person amongst us to the enemy lines.” [Ahmad and Al-Haakim]

Among the polytheists who were killed by the Prophet, sallallaahu ‘alayhi wa sallam, was the leader of the non-Muslims Ubay ibn Khalaf Al-Jumahi, as reported in the books of biographies. It is also reported that the Prophet, sallallaahu ‘alayhi wa sallam, said: “Allaah is very angry against a person who was killed by a Prophet.” [Al-Bukhari]

For more benefit, please refer to Fataawa in battle">84991 and 84678.

Allaah Knows best.