Monogamy, or restrictions by law to one wife, is not part of the economy of Heaven among men. Such a system was commenced by the founders of the Roman Empire. That empire was founded on the banks of the Tiber by wandering brigands. When these robbers founded the city of Rome, it was evident to them that their success in attaining a balance of power with their neighbours, depended upon introducing females into their body politic, so the stole them from the Sabines, where were their near neighbours. The scarcity of women gave existence to laws restricting one wife to one man. Rome became the mistress of the world, and introduced this order of monogamy wherever her sway was acknowledged. Thus this monogamic order of marriage, so esteemed by modern Christians as a holy sacrament and divine institution, is nothing but a system established by a set of robbers.
Brigham Young, 6 July 1862, Journal of Discourses 9:322
Young wants to deny history as well as the Bible. God's intent was for ONE wife or he would have given Adam more than one. Genesis 2:23-24:
And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man. Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh.
Notice he said the two shall be ONE flesh. In every instance in Scripture where a man has more than one wife, strife becomes part of their lives. In Deuteronomy 17 God tells His people that when they have a king, the king should not have many wives. This was centuries before the Roman empire and Young's story is nothing but 100% fiction not supported by actual history.
The truth is that Joseph Smith started the law of polygamy (claiming he got it from God) because he was caught having an affair way back when in Ohio; he was a womanizer and suddenly needed a word from God to excuse his sin of adultery and to allow him to pile of sexual conquests even with women already married to other men. Brigham Young was just as much a womanizer and follower on Smith's heel collecting multiple sexual conquests.
IF the prophecy truly came from God, mankind's rules would have no effect.