'Teaching' in the Bible

My dearly-loved friends, it is no new command that I am now giving you, but an old command which you have had from the very beginning. By the old command I mean the teaching which you have already received.

As for you, let the teaching which you have received from the very beginning continue in your hearts. If that teaching does continue in your hearts, you also will continue to be in union with the Son and with the Father.