Obligatory Charity Tax (Zakat)
Bukhari :: Book 2 :: Volume 24 :: Hadith 570
Narrated Al-Aswad:
'Aisha intended to buy Barira (a slave-girl) in order to manumit her and her masters intended to put the condition that her Al-wala would be for them. 'Aisha mentioned that to the Prophet who said to her, "Buy her, as the "Wala" is for the manumitted." Once some meat was presented to the Prophet and 'Aisha said to him, "This (meat) was given in charity to Barira." He said, "It is an object of charity for Barira but a gift for us."