Obligatory Charity Tax (Zakat)

Bukhari :: Book 2 :: Volume 24 :: Hadith 510

Narrated 'Uqba bin Al-Harith:

Once the Prophet offered the 'Asr prayer and then hurriedly went to his house and returned immediately. I (or somebody else) asked him (as to what was the matter) and he said, "I left at home a piece of gold which was from the charity and I disliked to let it remain a night in my house, so I got it distributed . "