Perhaps the word ‘command’ is too strong. The Greek isn't so much ‘command’; it's ‘convey’.
Don't apologize for these things. Don't be aggressive, be appealing, but teach as them as true with authority. We teach, we appeal, we persuade, we remonstrate with people. Sometimes you see preaching today, especially some of the internet preachers, and it consists of all kinds of motivational stuff to tickle the ears and to astonish and interest people. It isn't actually teaching them. When you teach, you have not only got to put things across, but you have also got to leave people with that information so that they learn it. So the preacher and the teacher will cover the same ground – hopefully in different and interesting ways – again and again, so that we all learn the doctrines and we learn the promises. It is no good giving us something which thrills us at the moment, and then runs from the mind. We are building up a body of the knowledge of God and his ways: the way of salvation first, the rules and duties of the Christian life, the promises and plans and purposes of God, the great character and nature of God. As the time goes by, the people are also proofed against false teaching.