How to persuade a grumpy person to be more tactful?

Be patient, there will always be the softest time in people's hearts. If you get it, then you have succeeded! A grumpy person also has a gentle side. Try to talk to him patiently. No matter what the other person's attitude is, you should be as steady as Mount Tai, so that the other person will feel that his temper will not come out slowly. Come on, try, adjust yourself, I believe you can convince!