Abu Bakr said, "By Allah! If they (pay me the Zakat and) withhold even a young (female) goat which they used to pay during the lifetime of Allah's Messenger (ﷺ), I will fight with them for it." `Umar said, "It was nothing but Allah Who opened Abu Bakr's chest towards the decision to fight, and I came to know that his decision was right."
Sahih al-Bukhari Book 24, Hadith 59
← Previous Hadith Abu Bakr wrote to me what Allah had ordered His Apostle (about Zakat) which goes: Neither an old nor a defected animal, nor a male-goat may be taken as Zakat except if the Zakat collector wishes (to take it).

Sahih al-Bukhari Book 24, Hadith 58 Next Hadith → When Allah's Messenger (ﷺ) (p.b.u.h) sent Mu`adh to Yemen, he said (to him), "YOU are going to people of a (Divine) Book. First of all invite them to worship Allah (alone) and when they come to know Allah, inform them that Allah has enjoined on them, five prayers in every day and night; and if they start offering these prayers, inform them that Allah has enjoined on them, the Zakat. And it is to be taken from the rich amongst them and given to the poor amongst them; and if they obey you in that, take Zakat from them and avoid (don't take) the best property of the people as Zakat."

Sahih al-Bukhari Book 24, Hadith 60