Obligatory Charity Tax (Zakat)

Bukhari :: Book 2 :: Volume 24 :: Hadith 493

Narrated Abu Huraira:

The Prophet said, "The Hour (Day of Judgment) will not be established till your wealth increases so much so that one will be worried, for no one will accept his Zakat and the person to whom he will give it will reply, 'I am not in need of it.' "