Not everyone can teach others about Christ

I know the title may seem strange, especially coming from a person who encourages people to talk to others about Jesus and trains them how to do it. Let me be clear, the restrictions on who can teach others about Christ are not my own opinions. These restrictions are set in place by God. I want to look at three different occasions when Jesus told people not to tell others important truths about Himself, discovering why, and then learning who is able to teach others.