Genesis Chapter 36
Esau had three wives. Two of them were from the daughters of Canaan. Rebekkah and Issac were disturbed with these two pagan wives of their son (Gen. 26:34). Esau never should have married these women. It is against Torah to marry Canaanites (Deut. 7:1-4). The drash, remez, or maybe even pashat message is that marriage to unbelievers or pagans is prohibited.