על כן: When the Torah Changes Voices

(24) Hence a man leaves his father and mother and clings to his wife, so that they become one flesh.

For this reason the text says since the female of the adam was a bone of his bones and flesh of his flesh, he cleaved to her and she was in his bosom like his own flesh and he desired her to be constantly with him. As this was so with Adam so was his nature transmitted to his progeny, to make the males, cleaving to their females, leaving their fathers and mothers and regarding their wives as if they were one flesh with them.

Similarly, “you are our brother, our flesh (gen.37:27), “to the meat of ones flesh (Lev.18:6), those close in family are called “meat of flesh” and so will leave the “meat” of his father and his mother and their closeness and see that his wife is closer to him than they are.

(27) When the boys grew up, Esau became a skillful hunter, a man of the outdoors; but Jacob was a mild man who stayed in camp.

(28) Isaac favored Esau because he had a taste for game; but Rebekah favored Jacob.

(1) יודע ציד, hunting venison and retrieving the animal to serve as food.

...An alternate interpretation. The words על כן, mean: “as a result of this,” i.e. as a result of having narrowly escaped death as a result of having remained exposed to danger alone during the night, the Israelites learned that this is not the correct way to behave at night and alone.

Abstaining from eating the thigh muscle is the visible reminder of the fact that this lesson had been internalised by the people as an inadmissible way to behave...

In the Book of the Wars of Adonoy. This was a separate Book, in which the Wars of Hashem on behalf of those who fear Him were written. Possibly, it existed in the days of Avraham, for many books were lost and are not extant anymore.

Such as the words of Nasan and Ido, the Divrei HaYamim of the Kings of Yisroel, the Songs of Shlomo and his Proverbs.