`Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that` when the Messenger of Allah (peace and blessings be upon him) passed away and Sayyiduna Abu Bakr as-Siddiq (may Allah be pleased with him) became the caliph, and the Arabs who were to become disbelievers became disbelievers, Sayyiduna Umar (may Allah be pleased with him) said to Sayyiduna Abu Bakr as-Siddiq (may Allah be pleased with him): How will you fight these people when the Messenger of Allah (peace and blessings be upon him) said, "I have been commanded to fight the people until they say La ilaha illallah. Whoever says La ilaha illallah has protected from me his wealth and his life except for a right due (i.e., as recompense for some offense, such as committing adultery or murder, then he will be seized), and his reckoning is with Allah." (If there is disbelief in his heart and he outwardly becomes Muslim out of fear, then on the Day of Judgment Allah will take his account. The world is based on what is apparent; in this world, there will be no accountability for him.) Sayyiduna Abu Bakr as-Siddiq (may Allah be pleased with him) said: By Allah, I will fight the one who differentiates between prayer and zakat, because zakat is the right of wealth. By Allah, if they withhold even a rope which they used to give to the Messenger of Allah (peace and blessings be upon him), I will fight them for withholding it. Sayyiduna Umar (may Allah be pleased with him) said: By Allah, then it was nothing but that I became certain that Allah, Glorified and Exalted is He, had opened the chest of Sayyiduna Abu Bakr (may Allah be pleased with him) for fighting (i.e., placed this matter in his heart). Then I knew that this was the truth.