Sahih Al Bukhari Hadith Number 1468

Narrated Abu Huraira: Allah’s Messenger (peace be upon him) (peace eb upon him) ordered (a person) to collect Zakat, and that person returned and told him that Ibn Jamil, Khalid bin Al-Walid, and `Abbas bin `Abdul Muttalib had refused to give Zakat.” The Prophet said, “What made Ibn Jamil refuse to give Zakat though he was a poor man, and was made wealthy by Allah and His Apostle ? But you are unfair in asking Zakat from Khalid as he is keeping his armor for Allah’s Cause (for Jihad). As for `Abbas bin `Abdul Muttalib, he is the uncle of Allah’s Apostle (peace eb upon him) and Zakat is compulsory on him and he should pay it double.”

24  Obligatory Charity Tax (Zakat)
Hadith number 1468
Volume no 2
Chapter: 49 (The Statement of Allah Ta’ala: “(Alms-tax should be spent)… to free the slaves; and for those in debt; and for Allah’s cause…” (9:60)