Ecclesiastes 9:17 says, "The words of the wise spoken calmly are heard." The wisest man in history, King Solomon, is teaching us that a wise person should always remain calm when speaking. Only in this way will their words be heard.
The same applies to any relationship, between friends, husband and wife, or work relationship; the person should always speak beNajat, calmly.
According to this explanation, calmness, so to speak, resides with the giver. Another way to read the verse is that the receiver must be calm in order to recognize the wisdom of the words being spoken. Even the most valid and clear explanations can be misinterpreted if the receiver is not ready to hear them.