كتاب المقدمات
1
The Book of Miscellany
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].
الثاني‏:‏ عن ابن مسعود رضي الله عنه أن رسول الله صلى الله عليه وسلم قال‏:‏ ‏ "‏ما من نبي بعثه الله في أمة قبلي إلا كان له من أمته حواريون وأصحاب يأخذون بسنته ويقتدون بأمره، ثم إنها تختلف من بعدهم خلوف يقولون مالا يفعلون ويفعلون ما لا يؤمرون، فمن جاهدهم بيده فهو مؤمن، ومن جاهدهم بقلبه فهو مؤمن، ومن جاهدهم بلسانه فهو مؤمن ، وليس وراء ذلك الإيمان حبة خردل‏"‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏‏.‏
Arabic/English book reference : Book 1, Hadith 185