Maliks Muwatta Book 17, Hadith Number 5.

Section : The Zakat on Gold and Silver Coin.

Yahya related to me from Malik from Urwa ibn Husayn from A’isha bint Qudama that her father said, “When I used to come to Uthman ibn Affan to collect my allowance he would ask me, ‘Do you have any property on which zakat is due? ‘If I said, ‘Yes,’ he would deduct the zakat on that property from my allowance, and if I said, ‘No,’ he would pay me my allowance (in full).”