Sayyidina Abu Hurairah (RA) reported that when Allah’s Messenger (SAW) died and Abu Bakr (RA) became Khalifah after him those of the Arabs who had to disbelieve, disbelieved. So, Umar ibn al-Khattab (RA) said to Abu Bakr (RA), "How will you fight people while Allah’s Messenger had said, ‘I have been commanded to fight people till they say 'There is no God but Allah' and when one says 'There is no God but Allah' he has saved from me his property and life save for the right against it, and the reckoning is with Allah.’ Abu Bakr (RA) said, “By Allah, I will fight those who differentiate between salah and zakah. While zakah is the right on property, by Allah, if they disallow me even a rope that they used to give to Allah’s Messenger (SAW), I will fight them over that.” Umar ibn al-Khattab (RA) said, “It was not, but that I observed that Allah had opened the heart of Abu Bakr ‘(RA) to fight and I knew that he was right."