31:19
And be moderate in your pace and lower [of] your voice. Indeed, (the) harshest (of all) sounds (is) surely (the) voice (of) the donkeys."

24:31
And say to the believing women (that) they should lower [of] their gaze and they should guard their chastity, and not (to) display their adornment except what is apparent of it. And let them draw their head covers over their bosoms, and not (to) display their adornment except to their husbands, or their fathers or fathers (of) their husbands or their sons or sons (of) their husbands or their brothers or sons (of) their brothers or sons (of) their sisters, or their women or what possess their right hands or the attendants having no (of) physical desire among [the] men or [the] children who (are) not aware of private aspects (of) the women. And not let them stamp their feet to make known what they conceal of their adornment. And turn to Allah altogether O believers! So that you may succeed.

24:30
Say to the believing men they should lower from their gaze and they should guard their chastity. That (is) purer for them. Indeed, Allah (is) All-Aware of what they do.

49:3
Indeed, those who lower their voices (in) presence (of the) Messenger (of) Allah - those, (are) the ones has tested Allah their hearts for righteousness. For them (is) forgiveness and a reward great.