Sahih Bukhari Volume 4, Book 56, Hadith Number 728.

Narated By Abu Huraira : The Prophet said, “O Bani ‘Abd Munaf! Buy yourselves from Allah; O Bani ‘Abdul-Muttalib! Buy yourselves from Allah; O mother of Az-Zubair bin Al-Awwam, the aunt of Allah’s Apostle, and O Fatima bint Muhammad! Buy yourselves from Allah, for I cannot defend you before Allah. You (both) can ask me from my property as much as you like.”