What does the bible say about polyamorous/polygamous relationships?

Having/loving more than one partner.What does the bible say about polyamorous/polygamous relationships?
the bible doe not specifically forbid polygamy , however the apostle Paul suggested that if a man was going to be in church leadership that he should only have one wife ( presumably to prevent distraction from spiritual matters) Polyamorality on the other hand is adulterous and therefore forbidden.What does the bible say about polyamorous/polygamous relationships?
what does the Koran say?
Why does it matter what a 6000 year old book written in a language almost no one can read says?