Commentary for Genesis 27:39

משמני הארץ וגו THE FATNESS OF THE EARTH etc. — This refers to the Greek portions of Italy (Graeca Magna) (Genesis Rabbah 67:6).

BEHOLD (‘HINEI’), OF THE FAT PLACES OF THE EARTH SHALL BE THY DWELLING. The intent of the word hinei (behold) is: “Now I could give you of the fat places of the earth and of the dew of heaven, for of these there is sufficient [abundance] for both of you to have of the fat places of the earth and of the dew of heaven, but in the matter of lordship, that will be his, and you shall serve him.” Isaac also did not give him plenty of corn and wine as he gave to his brother since he wanted to honor the one who had been blessed first above him. Later he said to Jacob, And G-d Almighty give thee the blessing of Abraham… that thou mayest inherit the land of thy sojournings,²³⁷Further, 28:4. meaning that he should have the plentifulness of the corn and wine in the land of Canaan, which was Abraham’s gift, while Esau would have the dew and the fat places of the earth in another land.

הנה משמני הארץ יהיה מושבך, I am able to bless you, assuring you that you and your descendants will reside in fruitful areas of the earth, even if they will be marginally subservient to your brother.