Ge 26:34 When Esau was forty years old, he took as wives Judith the daughter of Beeri the Hittite, and Basemath the daughter of Elon the Hittite.

35 And they were a grief of mind to Isaac and Rebekah.

Here we are shown the defiance of Esau. He surely must have known that God made a thumbs down sign against these people for their wickedness (Gen. 15: 16-21). He surely must have known about his grandfather's (Abraham) concern that his father (Isaac) should not be married to these women (Gen. 24:3) and yet here he shows his lack of interest in his family's special place and calling in God's program by marrying these Canaanites (the Hittites were one of the Canaanites).    

Moses is showing his Israelite readers about Esau's attitude to God's covenant blessings promised to his fathers. He is not committed to it. Therefore the line of blessing is to go to Jacob.

Ge 26:26 Then Abimelech came to him from Gerar with Ahuzzath, one of his friends, and Phichol the commander of his army.

27 And Isaac said to them, "Why have you come to me, since you hate me and have sent me away from you?"

28 But they said, "We have certainly seen that the LORD is with you. So we said, 'Let there now be an oath between us, between you and us; and let us make a covenant with you,

29 'that you will do us no harm, since we have not touched you, and since we have done nothing to you but good and have sent you away in peace. You are now the blessed of the LORD.'"

30 So he made them a feast, and they ate and drank.

31 Then they arose early in the morning and swore an oath with one another; and Isaac sent them away, and they departed from him in peace.

32 It came to pass the same day that Isaac's servants came and told him about the well which they had dug, and said to him, "We have found water."

33 So he called it Shebah. Therefore the name of the city is Beersheba to this day.

Moses is encouraging his fellow Israelite readers here that God can provide for them ("We have found water") and cause them to live in peace with their neighbors, yes even with those who hate them. He used the story of their forefather Isaac to illustrate and demonstrate his point. This was to stir Israel on to obedience and claim the promises that God made to them:

De 28:12 "The LORD will open to you His good treasure, the heavens, to give the rain to your land in its season, and to bless all the work of your hand. You shall lend to many nations, but you shall not borrow.

De 28:10 "Then all peoples of the earth shall see that you are called by the name of the LORD, and they shall be afraid of you.

De 28:13 "And the LORD will make you the head and not the tail; you shall be above only, and not be beneath, if you heed the commandments of the LORD your God, which I command you today, and are careful to observe them.

Ge 26:15 Now the Philistines had stopped up all the wells which his father's servants had dug in the days of Abraham his father, and they had filled them with earth.

16 And Abimelech said to Isaac, "Go away from us, for you are much mightier than we."

17 Then Isaac departed from there and pitched his tent in the Valley of Gerar, and dwelt there.

18 And Isaac dug again the wells of water which they had dug in the days of Abraham his father, for the Philistines had stopped them up after the death of Abraham. He called them by the names which his father had called them.

19 Also Isaac's servants dug in the valley, and found a well of running water there.

20 But the herdsmen of Gerar quarreled with Isaac's herdsmen, saying, "The water is ours." So he called the name of the well Esek, because they quarreled with him.

21 Then they dug another well, and they quarreled over that one also. So he called its name Sitnah.

22 And he moved from there and dug another well, and they did not quarrel over it. So he called its name Rehoboth, because he said, "For now the LORD has made room for us, and we shall be fruitful in the land."

Moses is showing his Israelite readers here that just as nothing and no one was able to hinder Isaac from being blessed so nothing and no one can hinder God's blessings to Israel. The Lord Himself will make room for them in the land and bless them there.

Ge 26:7 And the men of the place asked about his wife. And he said, "She is my sister"; for he was afraid to say, "She is my wife," because he thought, "lest the men of the place kill me for Rebekah, because she is beautiful to behold."

8 Now it came to pass, when he had been there a long time, that Abimelech king of the Philistines looked through a window, and saw, and there was Isaac, showing endearment to Rebekah his wife.

9 Then Abimelech called Isaac and said, "Quite obviously she is your wife; so how could you say, 'She is my sister'?" And Isaac said to him, "Because I said, 'Lest I die on account of her.'"

10 And Abimelech said, "What is this you have done to us? One of the people might soon have lain with your wife, and you would have brought guilt on us."

11 So Abimelech charged all his people, saying, "He who touches this man or his wife shall surely be put to death."

12 Then Isaac sowed in that land, and reaped in the same year a hundredfold; and the LORD blessed him.

13 The man began to prosper, and continued prospering until he became very prosperous;

14 for he had possessions of flocks and possessions of herds and a great number of servants. So the Philistines envied him.

The whole point of these verses is this---Moses is highlighting God's faithfulness to his Israelite readers through the life of their forefather Isaac. Back in verse 3, God assured Isaac: "Dwell in this land, and I will be with you and bless you..."

Moses intentionally recounted the parallel events of Abraham's life and Isaac's life to show that in both lives God was faithful. The point is this----"He could be just as faithful to you Israelites who are their descendants."

This should encourage them to be faithful to God in response and not turn to other gods.