as salam alaikum
The Qur'an says:
"...and do not mix truth with falsehood" (2:42)
"...and speak kindly to people" (2:83)
"...and speak to them honorable words" (4:5).
"Allah does not like the broadcasting of anyone's evil in speech except by someone who has been wronged" (4:148)
"Do not abuse those whom they invoke besides Allah, lest they should abuse Allah out of hostility" (6:108)
"And when you speak be fair" (6:152)
"Indeed the hearing, the eyesight and the heart: all of these are accountable" (17:36).
"Tell My servants to speak in a manner which is the best" (17:53)
"Avoid false speech" (22:30)
"Lower your voice, indeed the ugliest of voices is the donkey's voice" (31:19).
"O you who have faith! Be wary of Allah and speak upright words" (33:70)
"How regrettable of the servants! There did not come to them any messenger but that they used to deride him" (36:30)
"O you who have faith! Let not any people ridicule another people: it may be that they are better than they are; nor let women ridicule women: it may be that they are better than they are. And do not defame one another, nor insult one another by nicknames. An evil name is transgression after faith! And whoever is not penitent, such are the wrongdoers" (49:11)
"Do not spy or backbite one another. Will any one of you love to eat the flesh of his dead brother?" (49:12).
With prayers for your success.