ETIQUETTE OF GATHERINGS:

O you who believe, do not enter into others houses, without permission if it is said to you, ‘Go back’, just go back; Greet with Salaam to one's another when you enter homes, if it is said to you, make room in your assemblies, then make room; and if it is said, “rise up”, then rise up, do not display yourselves like that of the time of ignorance, talk to each other in the best way, don't whisper, nor speak aloud, don't scoff each other, don't call anyone with evil titles, don't be curious and beware of suspicions, don't backbite nor slandered anyone, when you have had the meal, just disperse, and do not sit for meaningless chat. Indeed, good deeds erase bad deeds. That is an admonition for the mindful.

Allah says:

O you who believe, do not enter any houses, other than your own houses unless you seek permission and greet their inmates with Salam. That is good for you, so that you may be heedful. Even if you do not find anyone in them, do not enter therein until permission is given to you. And if it is said to you, ‘Go back’, just go back; it is more purer for you. Allah is All-Aware of what you do.
(24:27,28)

When you enter homes, greet one's another with Salam, a greeting prescribed by Allah, is blessed, pleasant. This is how Allah explains the verses to you, so that you may understand.
(24:61)

O you who believe, when it is said to you, “Make room (for others) in the sitting's”, then make room, and Allah will make room for you. And when it is said, “Rise up”, then rise up.
(58:11)

And stay in your houses, and do not display yourselves like that of the times of ignorance, and establish Salah, and pay Zakah, and obey Allah and His Messenger. Allah only intends to keep all sorts of filth away from you, O members of the family and to make you pure through a perfect purification.
(33:33)

Say to My slave that, they should speak that which is best. Surely, Satan creates discord among them. Indeed, Satan is an open enemy to mankind.
(17:53)

There is no good in most of their whispers, unless one's bids charity or a fair action, or reconciliation among people. The one's who does this, to seek Allah’s pleasure, We shall give him a great reward.
(4:114)

And be moderate in your walk, and lower your voice. Surely, the ugliest of voices is the voice of the donkeys.”
(31:19)

O you who believe, no group should ever scoff at another group. May be, the latter is better than the former. Nor should women at other women. May be, the latter women are better than the former ones. Nor defame one's another, nor call one's another with bad nicknames. Evils is the name of rebellion after having Faith. If anyone does not repent, then such people are the wrongdoers. O you who believe, abstain from many of the suspicions. Some suspicions are sins. And do not be curious, and do not backbite one's another. Does one's for you like that he eats the flesh of his dead brother? You would hate it. And fear Allah. Surely Allah is the One's Who forgives and accepts repentance, Most Merciful.
(49:11,12)

Whoever commits a mistake or a sin, then shifts its blame to an innocent person, he indeed takes the burden of a false imputation and a glaring sin.
(4:112)

O you who believe, do not enter the houses of the Prophet, unless you are permitted for a meal, not to wait for its preparation. But when you are invited, go inside. Then, once you have had the meal, just disperse, and do not sit being keen for a chat. This hurts the Prophet, but he feels shy of you, but Allah is not shy of the truth.
(33:53)

Surely, good deeds erase bad deeds. That is an admonition for the mindful.
(11:114)