Abdullah bin Mas'ud (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Never a Prophet had been sent before me by Allah to his people but he had, among his people, (his) disciples and companions, who followed his ways and obeyed his command. Then there came after them their successors who proclaimed what they did not practise, and practised what they were not commanded to do. And (he) who strove against them with his hand is a believer; he who strove against them with his heart is a believer; and he who strove against them with his tongue is a believer ; and beyond that there is no grain of Faith".[Muslim].
Arabic/English book reference: Book 1, Hadith 185