Why was Esau a grief of mind to Isaac and Rebekah?
Esau was a grief of mind to Isaac and Rebekah because of his unbelief. In that unbelief he married Canaanite women. The context groups Esau's grief with Ishmael and Saul as examples of unbelief, showing that refusing to believe God's Word led to actions that deeply grieved his parents.
Les teaches that Esau was a grief of mind to Isaac and Rebekah because of his unbelief. The specific outworking was that in his unbelief he went and married Canaanite women. Les then broadens the pattern: Ishmael’s basic problem was unbelief, and Saul’s failure compared to David was also unbelief—even leading Saul to the witch of Endor. All through Scripture, mankind refused to believe the Word of God.