Joseph records a revelation in D&C 132 that lays out the concept of plural marriage.

Jul 12, 1843
Joseph Smith, Jr.

Revelation, 12 July 1843 [D&C 132], p. 5, The Joseph Smith Papers website, accessed December 20, 2021

The Joseph Smith Papers
Sarah, Abraham, Joseph Smith, Jr., Hagar
Members of The Church of Jesus Christ of Latter-day Saints

God commanded Abraham, and Sarah gave Hagar to Abraham to wife. and why did She do it? Because this was the law, and from Hagar Sprang many people. This Therefore was fulfilling, among other things, the promises Was Abraham therefore under condemnation? Verily I Say unto you nay for I the Lorde Commanded it. Abraham was Commanded to offer his Son Isaac; nevertheless it was written thou Shalt not kill, Abraham however did not refuse, and it was accounted unto him for righteousness, Abraham received Concubines, and they bare him Children, and it was accounted unto him for righteousness because they ware Given unto him. and he abode in my law, as Isaac also, and Jacob did none other things, than that which they were commanded and because they did none other things than that which they were commanded they have enterd into there exaltation according to the promises, and Set Sit upon thrones; and are not angels but are Gods. David also receiveth received many wives and Concubines and as also Solomon and Moses my Servents; as also many others of my Servents from the begenning of creation untill this time and in nothing did they Sin Save in those things which they received not of me. David<​s​> wives and Concubines were given unto him of me by the hand of Nathan my Servent and others of the prophets who had the Keys of this power; and in none of these things did he Sin against me Save in the case of Uriah and his wife and therefore he hath fallen from his exaltation and received his portion and he Shall not inherit them out of the world for I gave them unto another Saith the Lord, I am the Lord, thy God and I gave unto thee my Servent Joseph an appointment and restore all things ask what ye will and it Shall be given unto you according to my word. . . .

Copyright © B. H. Roberts Foundation
The B. H. Roberts Foundation is not owned by, operated by, or affiliated with the Church of Jesus Christ of Latter-day Saints.