Matthew 5:31-32
It was also said [Deut. 24:1-3], 'Whoever divorces his wife, let it be done with a [legally binding] divorce decree, which he must give her.'
Luke 16:18
"Every person who divorces his wife and marries another woman becomes sexually unfaithful to her [i.e., because he is still regarded by God as married to his first wife. See Matt. 19:9]. And the person who marries someone who has been divorced by her husband commits sexual sin with her [i.e., because she is still rightfully married to her first husband].
Matthew 19:3-9
Some Pharisees came to Him, [attempting] to put Him to a test. They said, "Is it permissible by the law of Moses for a man to divorce his wife for any reason [he chooses]?"
Mark 10:2-12
Some Pharisees [i.e., a strict sect of the Jewish religion] came to Him [and attempted] to test Him by asking, "Is it permissible by the law of Moses for a man to divorce his wife?"