I head the Messenger of Allah (ﷺ) say: If any one you sees something objectionable, he should change it with his hand if he can change it with his hand. (The narrator Hammad broke the rest of the tradition which was completed by Ibn al-‘Ala’.) But if he cannot (do so), he should do it with his tongue, and if he cannot (do so with) his tongue he should do it in his heart, that being the weakest form of faith.

Sunan Abi Dawud Book 39, Hadith 50