Leadership - communication

I heard recently in some radio:

"I can only take responsibility for what I say, but I can't take the responsibility for what you understand."

At the beginning I thought that this is very true, but later I realised that I spent a lot of time at work to make sure that people understand what I say. I believe that this is one of the most important skills for a good leader and a leader is a person who must take responsibility for that.