Musnad Ahmad 33:80

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Muharib, who said: I heard Jabir ibn Abdullah saying: I sold a camel to the Messenger of Allah (peace and blessings of Allah be upon him) during a journey. When we arrived in Medina, the Prophet (peace and blessings of Allah be upon him) said: "Go to the mosque and pray two rak'ahs." Then he weighed [the payment] for me—Shu'bah said: Or he ordered that it be weighed for me—and he gave me extra. Some of it remained with me until the people of Ash-Sham took it on the day of Al-Harrah.