Walaikum Salaam. Peace be upon you!. Here are some quotes :
“Do not concern yourself with things about which you have no knowledge. Verily, your hearing, sight, and heart -- all of them will be called to account" (Quran 17:36).
"O ye who believe! let not a people ridicule [another] people; perhaps they may be better than them; nor let women ridicule [other] women; perhaps they may be better than them. And do not insult one another and do not call each other by [offensive] nicknames. How terrible is the defamation after having faith!. And whoever does not repent - then it is those who are the wrongdoers.
O ye who believe! Avoid suspicion as much (as possible): for suspicion in some cases is a sin: And do not spy or backbite each other. Would any of you like to eat the flesh of his dead brother? Nay, ye would abhor it...But fear Allah: For Allah is Oft-Returning, Most Merciful." - [49:12-13]
"Why do not the believing men and women, whenever such [a rumour] is heard, think the best of one another and say, “This is an obvious falsehood”? ... When you take it up with your tongues, uttering with your mouths something of which you have no knowledge, you deem it a light matter. Whereas in the sight of God it is an awful thing!" (24:12-15).
The Prophet Muhammad once asked his followers, “Do you know what backbiting is?” They said, “Allah and His Messenger know best.” He continued, “Saying something about your brother that he dislikes.” Someone then asked, “What if what I say about my brother is true?” The Prophet Muhammad responded: “If what you say is true then you have backbitten about him, and if it is not true, then you have slandered him.”