Zakat (Kitab Al-Zakat)
Dawud :: Book 9 : Hadith 1577
Narrated Abdullah ibn Mu'awiyah al-Ghadiri:
AbuDawud said: I read in a document possessed by Abdullah ibn Salim at Hims: Abdullah ibn Mu'awiyah al-Ghadiri reported the Prophet (peace_be_upon_him) as saying: He who performs three things will have the taste of the faith. (They are:) One who worships Allah alone and one believes that there is no god but Allah; and one who pays the zakat on his property agreeably every year. One should not give an aged animal, nor one suffering from itch or ailing, and one most condemned, but one should give animals of medium quality, for Allah did not demand from you the best of your animals, nor did He command you to give the animals of worst quality.