The Bible teaches that bad company corrupts good morals (1 Corinthians 15:33). This is true and observable in the simplest of ways. When people surround themselves with others that have skewed moral foundations, its only a matter of time until their own moral foundation becomes skewed. This is the reason that God commanded the children of Israel to stay amongst themselves in marriage relationships, and why Israel became so corrupt when they disobeyed God and married foreigners as God commanded them not to.
In Genesis 26:34-35 the Bible provides a simple testimony of the wives of Esau. The Bible simply explains that Esau took two wives for himself that were named Judith and Basemath. The first problem can be identified in that Esau took on two wives. As has been mentioned in previous studies, God desired for man to take on one wife, and a wife to take on one husband. The Bible clearly shows that when this order is changed, problems arise. The testimony of Esau is no exception. The second problem is revealed in the subtle detail regarding the nationality of Esau's wives. The scriptures state that Judith and Basemath were both Hittite women. While some might not consider this to be a big deal, one must consider the history of the Hittite civilization. These people were polytheistic. The Hittites worshiped many gods, and all of them were false gods. The Hittite people did not have an understanding of the one true God that revealed Himself to Abraham. The Hittite gods were gods that often appealed to the flesh of the people in order to facilitate the desires of their flesh.
This would eventually create problems. Genesis 26:34-35 reveals that when Esau married these women at 40 years old, the three of them sought to make life difficult for Isaac and Rebekah. The children were frustrating the parents. This detail suggests that Isaac and Rebekah were not pleased with the choices that Esau made to marry these women. However, their frustration is their own fault. The scriptures never reveal Isaac being clear and specific that Esau should marry a woman who worshiped God. Yet the scriptures do show Isaac giving this clear instruction to Jacob in Genesis 28:1. When Abraham sent his servant out to find a wife for Isaac, the instruction was made clear that Abraham desired a woman within the family that knew and worshiped God. Isaac's lack of emphasis on this point helped create a set of circumstances that would create difficulty for Isaac and Rebekah, as well as Jacob.
The character of Esau is very well defined in scripture. Esau was a "man's man" that hunted. Esau was a man that desired to selfishly feed the desires of his flesh. Esau was a man that had little to no perspective on eternity, and thus despised his birthright. Even if Isaac would have told Esau to marry a woman that knew and worshiped God, it is difficult to say if Esau would have done so. Hence, it is no surprise that Esau took on, not one, but two wives that worshiped false gods, thereby making his struggles far more complex and difficult to deal with. Though Esau goes on to live, the scriptures reveal that the sum of his life did not please God in any sort of way and Esau was cut off from God. In fact, the Book of Hebrews states that Esau got to a point in his life where it became "impossible" to repent. These are the types of decisions that led Esau to that point of no return to God. Esau chose to satisfy his flesh and compromise his walk by surrounding himself with people who just didn't care about God. Eventually those types of decisions would mount to a tragic end for Esau - powerful lesson!