جامع الترمذي

Narrated Abu Hurairah: said: "When the Messenger of Allah (ﷺ) died and Abu Bakr became the Khalifah after him, whoever disbelieved from the Arabs disbelieved, so Umar bin Al-Khattab said to Abu Bakr: 'How will you fight the people while the Messenger of Allah (ﷺ) has said: 'I have been ordered to fight the people until they say La Ilaha Illallah, and if they say that, then their blood and wealth will be protected from me, except what it makes obligatory upon them, and their reckoning is with Allah?' So Abu Bakr said: 'By Allah I will fight whoever differentiates between Salat and Zakat. For indeed, Zakat is the right due upon wealth. And by Allah! If they withhold even (camel) tethers which they used to give to the Messenger of Allah (ﷺ) I will fight them for withholding it.' So Umar bin Al-Khattab said: 'By Allah! I saw that Allah had opened Abu Bakr's chest to fighting, so I knew that it was correct.'"