D&C 49

 Correcting the philosophy of the Shaking Quakers, the Lord clearly presents "the plan" - 

 "...verily I say unto you, that whoso forbiddeth to marry is not ordained of God, for marriage is ordained of God unto man.

16 Wherefore, it is lawful that he should have one wife, and they twain shall be one flesh, and all this that the earth might answer the end of its creation;

17 And that it might be filled with the measure of man, according to his creation before the world was made."  (Doctrine and Covenants 49:15–17)