The command to fight the people until they say "La ilaha illallah Muhammad Rasul-Allah", and establish Salat, and pay the Zakat, and believe in everything that the prophet (ﷺ) brought. Whoever does that, his life and his wealth are protected except by its right, and his secrets are entrusted to Allah, the most high. Fighting those who withhold Zakat or other than that is one of the duties of Islam and the Iman should be concerned with the Laws of Islam
Abu Musa reported Allah's Messenger (ﷺ) as saying:
When Allah, the Exalted and Glorious, intends to show mercy to an Umma from amongst His servants He calls back His Apostle to his eternal home and makes him a harbinger and recompense in the world to come; and when He intends to cause destruction to an Umma, He punishes it while its Apostle is alive and He destroys it as he (the Apostle) witnesses it and he cools his eyes by destruction as they had belied him and disobeyed his command.
Reference: Sahih Muslim 2288 In-book : Book 43, Hadith 28 USC-MSA web (English) : Book 30, Hadith 5679 (deprecated)
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