Sahih Bukhari Volume 5, Book 59, Hadith Number 569.

Narrated By Salama bin Al-Akwa : I fought in seven Ghazwat (i.e. battles) along with the Prophet and fought in nine battles, fought by armies dispatched by the Prophet. Once Abu Bakr was our commander and at another time, Usama was our commander.

Narrated Salama in another narration: I fought seven Ghazwat (i.e. battles) along with the Prophet and also fought in nine battles, fought by armies sent by the Prophet. Once Abu Bakr was our commander and another time, Usama was (our commander).