D&C 42

When it comes to teaching the gospel, the Lord gave the following law -

"...the elders, priests and teachers of this church shall teach the principles of my gospel, which are in the Bible and the Book of Mormon, in the which is the fulness of the gospel.
13 And they shall observe the covenants and church articles to do them, and these shall be their teachings, as they shall be directed by the Spirit.
14 And the Spirit shall be given unto you by the prayer of faith; and if ye receive not the Spirit ye shall not teach."  (Doctrine and Covenants | Section 42:12 - 14)

And suggesting that there would be more eternal things revealed -

"And all this ye shall observe to do as I have commanded concerning your teaching, until the fulness of my scriptures is given."  (Doctrine and Covenants | Section 42:15)