Participation in Battles
Hazrat Ubayy (ra) participated in all the battles alongside the Holy Prophet (sa) including the battle of Badr, Uhud and Khandaq [the Ditch].
(Ibn Saad, Al-Tabaqat al-Kubra, Vol. 3 [Beirut, Lebanon: Dar al-Kutub al-Ilmiyyah, 2017] 378)