Narrated Jabir bin ‘Abdullah:
I sold a camel to the Prophet on one of the journeys. When we reached Medina, he ordered me to go to the Mosque and offer two Rakat. Then he weighed for me (the price of the camel in gold) and gave an extra amount over it. A part of it remained with me till it was taken by the army of Sham on the day of Harra.”
Sahih Bukhari, Volume 3, Book47, Number 775