Obligatory Charity Tax (Zakat)

Bukhari :: Book 2 :: Volume 24 :: Hadith 509

Narrated Ibn 'Umar:

I heard Allah's Apostle (p.b.u.h) while he was on the pulpit speaking about charity, to abstain from asking others for some financial help and about begging others, saying, "The upper hand is better than the lower hand. The upper hand is that of the giver and the lower (hand) is that of the beggar."