Fiqh-us-Sunnah Volume 3, Zakaat and Fasting, Fiqh 3.042A.

Zakah is not applicable to animals other than cattle. Thus, there is no zakah on horses, mules, or donkeys unless they are used for the purpose of trade. On the authority of ‘Ali, it is related that the Prophet, upon whom be peace, said: “I have exempted you from paying sadaqah on horses.” It was narrated by Ahmad and Abu Dawud with a good chain. On the authority of Abu Hurairah, it is related that the Messenger, upon whom be peace, was asked if there is zakah on donkeys. He replied: “Nothing was ever mentioned [in revelation] except in the following excellent Qur’anic verse: ‘And whosoever does evil equal to an atom’s weight will see it’ [azZalzalah 7-8].” It was narrated by Ahmad and its details have already been mentioned.

Harithah ibn Madrab reported that he performed pilgrimage (hajj) with Caliph ‘Umar, and the notables of Syria came to him and said: “O Commander of the Faithful, we have acquired some animals, so take from our property a sadaqah that purifies us.” He answered them: “My two predecessors [the Prophet, upon whom be peace, and Caliph Abu Bakr] did not do this before. But wait and let me ask the Muslims about this.” This was narrated by alHaythami, who said that it was narrated by Ahmad and atTabarani in the book entitled al-Kabir. The narrators of this hadith are considered trustworthy.

Az-Zuhri reported from Salman ibn Yassar that the people of Syria said to Abu ‘Ubaidah ibn al-Jarrah: “Take from our horses… a sadaqah.” He refused. Then he wrote to ‘Umar, who also refused. They spoke to him again, and he wrote to ‘Umar once again. ‘Umar wrote back: “If they desire that, take it from them and give it back to them [their poor] and to their slaves.” This was narrated by Malik and al-Baihaqi.