I heard the Messenger of Allah ﷺ say, "Whoever among you sees an evil, let him change it with his hand. If he is unable, then with his tongue. And if he is unable, then with his heart, and that is the weakest of faith."
أخبرنا محمد بن بشار قال حدثنا عبد الرحمن قال حدثنا سفيان عن قيس بن مسلم عن طارق بن شهاب قال
سمعت رسول الله ﷺ قال من رأى منكرا فليغيره بيده فإن لم يستطع فبلسانه فإن لم يستطع فبقلبه وذلك أضعف الإيمان
Reported by Muslim, Faith, chapter on explaining that forbidding wrong is part of faith, etc., hadith no. 49, from the hadith of Sufyan Thawri, with the same chain.