That is correct, how we talk and converse with people, our way of speaking matters a lot. The way we speak, tells who we are, and how we have been guided throughout our life. It tells a lot about our personality. We should always speak good and kind words for people. It reveals our identity as a person , as a human being. We will definitely find people with ravish and harsh behavior, but if we speak nicely with them also, it will make them to think about how good we were to them in-spite of their toughness with us. Speaking on time is also very important as indicated by Ramachandran Sir , because we need to know when we have to speak, especially in terms of discussions. Speak only when someone asks for your advice else remain quiet.
Stay happy and stay healthy :)
A positive attitude will lead to positive results.