Sahih Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Volume: 005 / Book Number: 059 / Hadith Number: 747
Narrated Abu Ishaq:
I asked Zaid bin Al-Arqam, "In how many Ghazawat did you take part in the company of Allah's Apostle?" He replied, "Seventeen." I further asked, "How many Ghazawat did the Prophet fight?" He replied, "Nineteen."