וַיָּ֥זֶד יַעֲקֹ֖ב נָזִ֑יד וַיָּבֹ֥א עֵשָׂ֛ו מִן־הַשָּׂדֶ֖ה וְה֥וּא עָיֵֽף׃
야곱이 죽을 쑤었더니 에서가 들에서부터 돌아와서 심히 곤비하여
Shenei Luchot HaBerit
Even when Esau wanted some of Jacob's soup, נזיר, prior to the transaction involving the sale of the birthright, it was Esau who practiced extreme deception as Rashi explains (25,29). Rashi says that the dish consisted of red lentils. How did Rashi know this? Or, at least, who told Rashi this? Rashi was not in the habit of making such a statement without quoting his source!