Ubaydullah bin Abdullah says: When people became apostates during the caliphate of Sayyiduna Abu Bakr (may Allah be pleased with him), Sayyiduna Umar (may Allah be pleased with him) said: O Abu Bakr! How can you fight these people, when the Messenger of Allah (peace and blessings be upon him) said that I have been commanded to fight the people until they say La ilaha illallah, and when they say La ilaha illallah, they will protect their blood and wealth from me, except by right, and their reckoning is with Allah the Exalted. But Sayyiduna Abu Bakr (may Allah be pleased with him) said: By Allah! I will surely fight those who differentiate between prayer and zakat, for zakat is the due right of wealth. By Allah, if they withhold even a single goat 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! I immediately realized that Allah the Exalted had opened the chest of Sayyiduna Abu Bakr (may Allah be pleased with him) for fighting, so I knew that this was the truth.