مسند أحمد

It was narrated that Abu Hurairah said: When the Messenger of Allah (ﷺ) died and some people apostatised, ‘Umar bin al-Khattab said: O Abu Bakr, how can you fight the people, when the Messenger of Allah (ﷺ) said: “I have been commanded to fight the people until they say La ilaha illallah (There is no god but Allah), and whoever says La ilaha illallah, his wealth and his life are protected from me, and his reckoning will be with Allah`? Abu Bakr said: I will most certainly fight those who separate prayer and zakah, for zakah is what is due on wealth. By Allah, if they withhold from me a small she-goat that they used to give to the Messenger of Allah (ﷺ), I will certainly fight them for withholding it. ʻUmar said: By Allah, as soon as I saw that Allah had opened Abu Bakr`s heart to the idea of fighting I knew that he was right.