Since a soft and kind speech with the audience has a significant impact in conveying the religious contents, the Holy Quran considering this issue has proposed a good and effective way in interacting and dealing with people, which if used properly has a great role in guiding others.
Therefore, if the speaker cares about the listeners and the audiences and speaks softly and properly, he would certainly see the effects of his beautiful words and speeches and wouldn,t stimulate the negative emotions of the listeners, in a way that his thoughts and attitudes are modest and humble in the face of the truth and this is the easiest way to convey the truth.
source : erfan.ir