Matthew 19:1-6 New International Version (NIV)
1 When Jesus had finished saying these things, he left Galilee and went into the region of Judea to the other side of the Jordan. 2 Large crowds followed him, and he healed them there.
3 Some Pharisees came to him to test him. They asked, “Is it lawful for a man to divorce his wife for any and every reason?"
4 “Haven’t you read,” he replied, “that at the beginning the Creator ‘made them male and female,’[a] 5 and said, ‘For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’[b]? 6 So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”
When Jesus said “Haven’t you read, that at the beginning the Creator made them male and female" I believe he was referring to Genesis 5:2.
2 He (God) created them male and female and blessed them. And he named them “Mankind” when they were created.
In regards to the unity of one man and one woman, how did the Pharisees as well as others listening to Jesus (Matthew 19:2-3) interoperate what Jesus meant (Matthew 19:4-6) when they would have also known that Abraham and King David had multiple wives and/or concubines?
NOTE: I don't want this to be about how Christians view polygamy today but rather how did those listening think/feel/interperate (through 1st century "eyes") what Jesus was now saying compared to the "views/actions" of their forefathers. Prior to Jesus referencing Genesis 5 and clarifying that the unity of male and female was orignially intended for one man and one woman, did those practicing Judaism and those following Jesus recognize a difference in what was once practiced and what is now being said; or did everyone already know the original intent of male and female, specifically in terms of how Jesus stated it to be in Matthew 19?