From the scriptures, Matthew 19 3:6

And Pharisees came up to him and
tested him by asking, “Is it lawful to divorce one's wife for any cause?” He answered,
“Have you not read that he who created them from the beginning made them male and female, and said, ‘Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh’? So they are no longer two but one flesh. What therefore God has joined together, let not man separate.”

God authorized Jesus Christ to reinstitute His original standard of monogamy,While I agree with monogamy , the Bible has many examples of men with more than one wife , and appears not to condemn this.