Some people do not speak clearly. They speak ambiguously and with formality. They consider the use of indications to be respectful. The listener sometimes does not get the message clearly and sometimes he understands wrongly. This causes much inconvenience. Therefore, speak up and speak clearly, without ambiguity.
Speak from in front of a person, not from behind. Speaking from behind a person is perplexing.
When renewing a request to a person, then mention it fully inspite of it having been stated before. Do not express yourself incompletely or ambiguously relying on an earlier explanation. It is possible that the earlier explanation has been partly forgotten, hence the listener may misunderstand the request if it is renewed without clarity.
Some people sitting at the back in a gathering clear their throats or cough in order to attract attention to themselves. If there is a real need to say something, go to the front and explain. However, this should not be done unnecessarily. It is improper to disturb a person involved in some work. Wait for the person to complete his task then address him.
Until such time that one topic has not been completed do not introduce another. While someone is speaking do not interrupt with another subject.
On making an enquiry reply in full, without ambiguity, when you are questioned. Do not reply with confusing statements which necessitate repeated questioning.
While eating, do not mention such things which nauseates or disgusts others. The disposition of some persons is delicate and cannot tolerate to hear the mention of disgusting things while eating.
In the presence of a sick person or his housefolk do not make such statements which causes them grief and to lose hope in life. Make encouraging statements to alleviate the pain and sorrow, Inshaa'Allah.
If you have to speak privately about a person who happens to be present, do not indicate this to another by means of the sign of the hand or eye. Do not let him realise that you are at all discussing him. This will apply if the discussion regarding him is permissible. If the discussion is not lawful, then discussing him will be sinful.
On hearing news of someone's illness, death, etc., do not publicise it until you have confirmed the truth of the news.
Rasoolullah sallallahu alayhi wasallam said: "Do not speak much besides Zikrullaah. Verily, abundant speech hardens the heart and the one with a hard heart is furthest from Allah." This applies to futile speech even though the talk may be lawful.
Imaam Maalik rahmatullahi
alayhi narrates that Hadhrat Eesaa alayhis salaam said: "Do not
speak in abundance for your heart will be hardened." In other words, fear and humility will be
eliminated from the heart. Experience confirms this fact.
Hadhrat Ali radhiyallahu anhu said that one should speak to people what they are unable to understand. Do not discuss with them things which are beyond their intellectual capacities. Hadhrat Ali radhiyallahu anhu added: "Do you wish them to refute Allah and His Rasool?" Some people will not hesitate to reject such Deeni narrations which they are unable to comprehend. Hadhrat Ibne Mas'ood radhiyallahu anhu said: "When you mention to people such things which ate beyond their intellectual capacities, then such talks will most certainly become a cause for the corruption of some people."
Do not unnecessarily adopt the speech styles and slang of those who are ignorant of the Deen.
Be moderate in speech. Do not expand the discussion so much that people become tired and perplexed nor abbreviate the talk to such an extent that the aim and object of the discussion are not understood.
A female should exercise care when speaking. She should not allow her voice to be heard by men unnecessarily. In like manner a man should not express himself sentimentally in the presence of females. It is obligatory that a should man abstain from reciting poetry and expressing himself melodiously in front of females (i.e. such females for whom the Shar'ee law of Hijaab applies).
Do not mumble when speaking. Speak with clarity.
Be to the point. Do not beat about the bush when speaking.
Think before speaking. Sometimes a wrong statement uttered without thinking leads to Jahannam. One will obtain salvation from this calamity by inculcating the habit of thinking before speaking.
Do not
insult anyone. Do not say to anyone: 'Faasiq, kaafir, Mal'oon (cursed), the enemy of Allah 
.
Do not be two-tongued, expressing views in the presence of a person calculated to please him, but when in the company of one holding another view, then speaking to please him.
Never engage in gossip, slander and scandalising. However, it will be permissible to speak contrary to fact and reality in order to restore peace and good relationship between antagonists or enemies.
Do not flatter anyone.
Do not become embroiled with anyone in obstinate debate and argument. When you realise that the person is not prepared to accept the truth, maintain silence. Do not become intransigent and bigoted. Bigotry is exceptionally evil.
Abstain from statements in which there is neither Deeni benefit nor worldly benefit.
Do not
curse or speak ill of time (the age). Time is blameless. By implication, the criticism is directed to Allah . We seek refuge
in Allah .
Do not praise those who are not upholders of the Deen. (Abstention from praising them should not be construed to mean permissibility to hold them in contempt. It is not permissible to despise them nor to adopt a holier than thou attitude.)
It is haraam to speak ill (Gheebat) of even children, insane persons and non-Muslims.
To deliberately listen to Gheebat being spoken is as if one has made Gheebat.
Juniors should not call their seniors by their names. They should adopt a name or title of respect and honour.
When meeting someone casually, e.g. along the road or by chance, do not engage in a topic which you will not be able to complete in the short while you are with him. If by the time of separating, the topic has not been concluded, you will either waste your time to complete the story or you will depart with the story unfinished. This leaves the listener in suspense and doubt.
If a person mistakes you for another, then immediately rectify him and state your identity.
In the presence of others do not use such terms which are considered uncultural. Express yourself in a cultured way, e.g. say 'the call of nature', etc.
Where the company consist of three persons, two should not speak by whispering to each other, nor should they ask the third one to leave, nor should they speak in a language which the third person does not understand. This causes distress to him.