Ubaidullah bin Abdullah narrates: Sayyiduna Abu Hurairah (may Allah be pleased with him) reported: When the Prophet Muhammad (peace and blessings be upon him) passed away and after him Sayyiduna Abu Bakr (may Allah be pleased with him) became the Caliph, some people from among the Arabs turned to disbelief. Sayyiduna Umar (may Allah be pleased with him) said: O Abu Bakr! How will you fight with the people when the Prophet Muhammad (peace and blessings be upon him) said: "I have been commanded to fight the people until they testify that there is no deity except Allah. Whoever says: There is no deity except Allah, then he has protected his wealth and his life from me, except for its due right, and his reckoning is with Allah." Sayyiduna Abu Bakr (may Allah be pleased with him) replied: By Allah! I will fight with the one who differentiates between prayer and zakat. Indeed, zakat is the due right of wealth. By Allah! If they withhold from me even a young she-goat which they used to give to the Prophet Muhammad (peace and blessings be upon him), I will fight them for withholding it. Sayyiduna Umar (may Allah be pleased with him) says: I realized that Allah had opened the heart of Sayyiduna Abu Bakr (may Allah be pleased with him) regarding fighting, and I came to know that this was the correct matter.