(Verse 30) And Esau said to Jacob: Give me a taste of that red stew, for I am famished. That is why he was called Edom. Red or tawny is called Edom in the Hebrew language. Therefore, from the fact that he sold his birthright for red food, he obtained the name Edom, which means tawny.
Let frugality be joined to fasting. Just as overeating is to be censured, so stimulants of the appetite must be eliminated. It is not that certain kinds of food are to be detested but that bodily pleasure is to be checked. Esau was censured not for having desired a fat calf or plump birds but for having coveted a dish of lentils.
[AD 420] Jerome on Genesis 25:30