Abu Hurairah reported,

When the Messenger of Allah ﷺ passed away and Abu Bakr was appointed as his successor, some of the Arabs reverted to disbelief. Umar said, "Abu Bakr, how can you fight these people when the Messenger of Allah ﷺ said, 'I have been commanded to fight people until they declare that there is no god but Allah. Whoever says there is no god but Allah has secured his life and property from me, except for what is rightfully due, and his reckoning is with Allah'?"Abu Bakr replied, "By Allah, I will surely fight anyone who separates the prayer from the zakat, for zakat is the right due on wealth. By Allah, if they withheld from me even a young goat that they used to give to the Messenger of Allah ﷺ, I would fight them for withholding it."Umar said, "By Allah, as soon as I saw that Allah had opened Abu Bakr's heart to fighting them, I knew that he was right."

أخبرنا كثير بن عبيد عن محمد بن حرب عن الزبيدي عن الزهري عن عبيد الله بن عبد الله

عن أبي هريرة قال

لما توفي رسول الله ﷺ واستخلف أبو بكر وكفر من كفر من العرب قال عمر يا أبا بكر كيف تقاتل الناس وقد قال رسول الله ﷺ أمرت أن أقاتل الناس حتى يقولوا لا إله إلا الله فمن قال لا إله إلا الله عصم مني نفسه وماله إلا بحقه وحسابه على الله قال أبو بكر رضي الله عنه والله لأقاتلن من فرق بين الصلاة والزكاة فإن الزكاة حق المال والله لو منعوني عناقا كانوا يؤدونها إلى رسول الله ﷺ لقاتلتهم على منعها فوالله ما هو إلا أن رأيت الله عز وجل قد شرح صدر أبي بكر للقتال وعرفت أنه الحق