I read in Shariat & Tasawwuf, that even one word spoken unnecessarily brings darkness to the heart.

Answer

Much speech is a destructive spiritual malady, hence the Qur'aan Majeed states:

"Not a word is uttered, but it is recorded by an ever ready guard."

Every word that issues from the mouth is recorded by an Angel. No matter how insignificant the statement may appear to a person, it is recorded in a Clear Book, for which the utterer will be accountable on the Day of Qiyaamah.

People have absolutely no idea of the spiritual harm they inflict on their Baatin (Rooh/ spiritual heart) with the abundance of futile and haraam talk which they so unthinkingly disgorge. The manner of controlling this evil habit of futile talk is firstly to reduce contact with people. Meet them only when there is a need, and after the need has been accomplished, immediately terminate the meeting.

Then of utmost importance its to briefly - for a couple of seconds - reflect before speaking. When about to speak, remind yourself that the Angel is in front of you ready to record your words as the Qur'aan states. Reflect on the statement you are about to utter - Is it permissible or not? Will it please Allah Ta'ala or displease Him? Will it hurt the feelings of the person? Is there any valid benefit in the statement or not?

In the beginning such reflection will be onerous, but if you are constant in this exercise of brief reflection, then, Insha- Allah, it will become a reflex action. Without any strain and effort, you will gain the propensity of immediately recognizing the category of the statements you intend to utter. Everything for success requires some effort. Minus effort there will be no achievement.

heirs of the deceased.