Abu Dawud Book 13, Hadith Number 2966.
Narated By Umar ibn AbdulAziz : Al-Mughirah (ibn Shu’bah) said: Umar ibn AbdulAziz gathered the family of Marwan when he was made caliph, and he said: Fadak belonged to the Apostle of Allah (PBUH), and he made contributions from it, showing repeated kindness to the poor of the Banu Hashim from it, and supplying from it the cost of marriage for those who were unmarried. Fatimah asked him to give it to her, but he refused. That is how matters stood during the lifetime of the Apostle of Allah (PBUH) till he passed on (i.e. died).
When AbuBakr was made ruler he administered it as the Prophet (PBUH) had done in his lifetime till he passed on. Then when Umar ibn al-Khattab was made ruler he administered it as they had done till he passed on. Then it was given to Marwan as a fief, and it afterwards came to Umar ibn AbdulAziz.
Umar ibn AbdulAziz said: I consider I have no right to something which the Apostle of Allah (PBUH) refused to Fatimah, and I call you to witness that I have restored it to its former condition; meaning in the time of the Apostle of Allah (PBUH).