Sahih al-Bukhari 2296

It is related that Jabir ibn 'Abdullah said, "The Prophet, may Allah bless him and grant him peace, said, 'If the money from Bahrayn comes, I will give you such-and-such.' The money from Bahrayn did not come until after the Prophet, may Allah bless him and grant him peace, had died. When the money of Bahrayn arrived, Abu Bakr commanded that it be announced, 'Whoever has a promise from the Prophet, may Allah bless him and grant him peace, or a debt should come to us.' I came to him and said, 'The Prophet, may Allah bless him and grant him peace, told me such-and-such.' He gave me a double handful and I counted them and there were five hundred. He said, 'Take twice as much again.'" [This was the jizya tax.]