Zakat (Kitab Al-Zakat)
Dawud :: Book 9 : Hadith 1571
Narrated Mu'adh ibn Jabal:
When the Prophet (peace_be_upon_him) sent him to the Yemen, he ordered him to take a male or a female calf a year old for every thirty cattle and a cow in its third year for every forty, and one dinar for every adult (unbeliever as a poll-tax) or cloths of equivalent value manufactured in the Yemen.