Minutes from St. George Utah Stake conference; Erastus Snow recounts incidents relating to origins of plural marriage, including Joseph being commanded by an angel to practice it.
Erastus Snow, St. George Utah Stake Conference, General Minutes, June 17, 1883, Church History Library
The Prophet Joseph had said to him also "I have not bee obedient enough to this holy law and the Lord was angry with me—and an Angel met me with a drawn sword but I plead with the Lord to forgive me and he did so & I made the sacrifice required of my hand and by the help of the Lord I will obey his Holy Law"—
"I know that I went to the Prophet Joseph Smith and he approved my receiving in this Holy Covenant my wife Minerva, my second wife who is with me here to day—and that he sent his Brother Hyrum to perform the ceremony by which we became husband & wife"