حروب الردة
The caliph Abu Bakr, believed by Sunni Muslims to be Muhammad's successor, was the first to institute a statutory zakat system. Abu Bakr established the principle that the zakat must be paid to the legitimate representative of Muhammad's authority (i.e. himself). Other Muslims disagreed and refused to pay zakat to Abu Bakr, leading to accusations of apostasy and, ultimately, the Ridda wars.