It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: I have been commanded to fight the people until they testify that there is no god but Allah. When they testify to this, they will protect their blood and wealth from me, and their reckoning will be with Allah the Exalted. When Sayyiduna Abu Bakr (may Allah be pleased with him) assumed the caliphate and those who had turned apostate became apostates, Sayyiduna Abu Bakr (may Allah be pleased with him) intended to fight them. But Sayyiduna Umar (may Allah be pleased with him) said: How will you fight those who perform prayer? But Sayyiduna Abu Bakr (may Allah be pleased with him) said: By Allah! I will certainly fight those who refuse to pay zakat. By Allah, if they withhold even a single she-goat which they used to give as obligatory charity to Allah and His Messenger, I will fight them for it. Sayyiduna Umar (may Allah be pleased with him) said: When I saw that Allah had opened the chest of Sayyiduna Abu Bakr (may Allah be pleased with him) to fight those who refused zakat, I knew that this was the truth.