Zakat (Kitab Al-Zakat)
Dawud :: Book 9 : Hadith 1710
Narrated AbuSa'id al-Khudri:
Ali ibn AbuTalib found a dinar and he took it to Fatimah. She asked the Apostle of Allah (peace_be_upon_him) about it. He said: This is Allah's provision. Then the Apostle of Allah (peace_be_upon_him) ate out of the food (bought with it), and Ali and Fatimah also ate out of that food. But afterwards a woman came crying out about the dinar. The Prophet (peace_be_upon_him) said: Pay the dinar, Ali.