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 Allahʿ? 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 Bakrʿs heart to the idea of fighting I knew that he was right.  

عَنْ أَبِي هُرَيْرَةَ قَالَلَمَّا تُوُفِّيَ رَسُولُ اللهِ ﷺ وَكَفَرَ مَنْ كَفَرَ قَالَ قَالَ عُمَرُ بْنُ الْخَطَّابِ يَا أَبَا بَكْرٍ كَيْفَ تُقَاتِلُ النَّاسَ وَقَدْ قَالَ رَسُولُ اللهِ ﷺ أُمِرْتُ أَنْ أُقَاتِلَ النَّاسَ حَتَّى يَقُولُوا لَا إِلَهَ إِلَّا اللهُ فَمَنْ قَالَ لَا إِلَهَ إِلَّا اللهُ فَقَدْ عَصَمَ مِنِّي مَالَهُ وَنَفْسَهُ وَحِسَابُهُ عَلَى اللهِ ﷻ ؟ قَالَ أَبُو بَكْرٍ لَأُقَاتِلَنَّ مَنْ فَرَّقَ بَيْنَ الصَّلاةِ وَالزَّكَاةِ إِنَّ الزَّكَاةَ حَقُّ الْمَالِ وَاللهِ لَوْ مَنَعُونِي عَنَاقًا كَانُوا يُؤَدُّونَهَا إِلَى رَسُولِ اللهِ ﷺ لَقَاتَلْتُهُمْ عَلَيْهَا فَقَالَ عُمَرُ وَاللهِ مَا هُوَ إِلَّا أَنْ رَأَيْتُ أَنَّ اللهَ قَدْ شَرَحَ صَدْرَ أَبِي بَكْرٍ بِالْقِتَالِ فَعَرَفْتُ أَنَّهُ الْحَقُّ