Matthew 19:3-6

3 The Pharisees also came to Him, testing Him, and saying to Him, "Is it lawful for a man to divorce his wife for just any reason?"

4 And He answered and said to them, "Have you not read that He who made them at the beginning 'made them male and female,'

5 and said, 'For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh'?

6 So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate."