Is a Muslim sinful for remaining silent about enjoining good and forbidding evil if he loses courage, and is it permissible for him to condemn only with his heart when fearing verbal or physical violence upon seeing an evil?

Enjoining good and forbidding evil is a great communal obligation (fard kifayah) and one of the distinguishing features of the Muslim Ummah. If a Muslim is unable to perform it, its obligation is lifted from them, and they suffice with denouncing it in their heart, which is the weakest form of faith. If a Muslim woman fears a certain harm, she suffices with denouncing it in her heart, and this denouncement is never lifted from her. It is permissible to address those who commit evil and forbid them, even if it leads to harm that can be endured, as Allah Almighty says: "And be patient over what befalls you. Indeed, that is from the matters [requiring] determination."