Kommentar zu Bereschit 25:29

ויזד means boiling, as the Targum renders it.

ויזד יעקב נזיד. Jacob cooked food. Perhaps the reason Jacob did this was that he had observed how effective Esau's providing his father with delicious meals had been in cementing Isaac's love for him. He therefore tried to emulate his brother.

ויזד, the formulation of vayazed which normally should have been vayizad with a dagesh in the letter ז, the middle letter of the root, is not as unusual as it appears, [the author discussing this in detail in his grammar known as shoroshim. Ed] The meaning of the expression is that “he cooked a dish ויבשל נזיד;” the Torah reports that on a certain day when Yaakov had cooked a dish Esau returned from the hunt tired and found the dish Yaakov had cooked ready for eating. He requested to be given some of it so that he could eat it. The purpose of this story being recorded in the Torah is in order to contrast Yaakov’s virtues with Esau’s irresponsible way of looking at life. Not only that, but Esau considered the gobbling up of food as an end in itself, he was what our sages call a גרגרן, glutton. Yaakov, on the other hand, was so little concerned with the physical gratifications available on earth that when cooking for himself, he cooked a dish of lentils, the simplest undistinguished vegetable. If, in spite of his general outlook, Yaakov refused to share this dish with Esau unless the latter sold him his birthright, even though Essau was his brother, this demonstrates Yaakov’s intelligence and his moral principles which made it difficult for him to give something for which he had toiled to someone who was self-centered and who did not make any contribution to civilisation at all, assuming that whenever he felt ravenous he could demand to be gratified by what belonged to others. It is concerning people like Esau that Solomon said in Proverbs 22,16:נותן לעשיר אך למחסור, “(He who oppresses the poor) is like giving gifts to the rich. The end result is loss.”