كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(45)
Chapter: The dispatch of Usama bin Zaid to Al-Huraqat
(45)
باب بَعْثُ النَّبِيِّ صلى الله عليه وسلم أُسَامَةَ بْنَ زَيْدٍ إِلَى الْحُرَقَاتِ مِنْ جُهَيْنَةَ
Sahih al-Bukhari 4270

Narrated Salama bin Al-Akwa`:

I fought in seven Ghazwat (i.e. battles) along with the Prophet (ﷺ) 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.

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا حَاتِمٌ، عَنْ يَزِيدَ بْنِ أَبِي عُبَيْدٍ، قَالَ سَمِعْتُ سَلَمَةَ بْنَ الأَكْوَعِ، يَقُولُ غَزَوْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم سَبْعَ غَزَوَاتٍ، وَخَرَجْتُ فِيمَا يَبْعَثُ مِنَ الْبُعُوثِ تِسْعَ غَزَوَاتٍ، مَرَّةً عَلَيْنَا أَبُو بَكْرٍ، وَمَرَّةً عَلَيْنَا أُسَامَةُ‏.‏
Reference : Sahih al-Bukhari 4270
In-book reference : Book 64, Hadith 304
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 569
  (deprecated numbering scheme)