Genesis 25:28

And Izhak loved Esau, for words of deceit were in his mouth; but Rivekah loved Jakob.

BECAUSE THERE WAS VENISON IN HIS MOUTH. The commentators explained it as meaning either that he [Esau] gave venison into Isaac’s mouth, or that he brought Isaac venison. The act of giving or bringing is thus missing from the verse. Similarly: The set time which Samuel; But the Lord — presented or made — me as a mighty warrior.
It is possible to explain that Isaac loved Esau because there was always venison in the mouth of Isaac. All day he would desire to eat the venison, and it was always in his mouth. He would not eat anything else, and Esau was the one who brought it to him, as Scripture said, A cunning hunter.
In my opinion the correct interpretation is that it is a metaphor which tells us that Esau, in the mouth of his father, was a hunter, as a person is surnamed by his constant occupation. Similarly, Thy habitation is in the midst of deceit; of deceit.” But the verse refers to the people by their constant practice. likewise, But I am all prayer. of constant prayer.” And so they said in Bereshith Rabbah, “Good meat for his mouth, good drink for his mouth.”

כי ציד בפיו, the plain meaning corresponds to Onkelos, i.e. because he brought him venison to eat.

אוהבת את יעקב, for she was aware of his perfection, also because the prediction to her of the prophet had been that the senior son would be subservient to the junior one. The Torah had to mention first that Yitzchok loved Esau in order for us to understand what had motivated to bless Esau, and what had motivated Rivkah to deceive him into blessing Yaakov.

ויאהב יצחק את עשו, also Esau, not only Yaakov, even though he must have been aware that Esau was far less perfect than Yaakov.

ורבקה אוהבת את יעקב, she only loved Yaakov, recognising the wickedness of Esau.

ויאהב, there was no need to mention that Yitzchok loved Yaakov; clearly his love for Yaakov was constantly on the increase seeing that Yaakov was righteous, etc. Esau’s claim to his father’s love was due only to the venison he brought his father from his hunting expeditions.

בפיו. This meat was especially tasty. Moreover Yitzchok was already aged, being more than seventy years old, Clearly, unless Esau had been at least 12 years old at the time he would not have known how to hunt with bow and arrow.

ורבקה אוהבת את יעקב, exclusively; the reason was that Yaakov pursued a lifestyle that would lead to eternal life, whereas Esau did the opposite. Not only did he not lead a life leading to eternal life after death, but he actively forfeited even life on earth, exposing himself to needless dangers. Seeing that Yitzchok was aging and sitting at home most of the time, he was not aware of Esau’s doings and was easily led to believe that Esau led a virtuous life, basing his belief on the daily supply of venison his son provided for him. The story unfolds at a time when Yitzchok was already incapable of seeing well with his physical eyes. The story of the sale of the birthright is told primarily to illustrate the disdain with which Esau looked upon spiritual values as a valuable acquisition, something guaranteeing a person life beyond death.