Joseph's revelation from 1831 affirms marriage is ordained of God.
Joseph Smith, Revelation, May 7, 1831 [D&C 49], Revelation Book 1, The Joseph Smith Papers website, accessed June 15, 2022
A Revelation given to Sidney [Rigdon] & Parley [P. Pratt] & Leman [Copley] Received at Kirtland Geauga Ohio th[e]ir mission to the Shakers & thus saith the Lord unto them as follows
. . .
& again I say unto you that whoso forbideth to marry is not ordained of God for it is ordained of God unto man wherefore it is lawful that he should have one wife & they twain shall be one flesh & all this that the Earth might answer the end of its Creation & that it might be filled with the measure of man according to his creation before the world was made . . .