Genesis 43:32

That is an abomination to the Egyptians The most generally received opinion has been, according to the paraphrases of Onkelos and Jonathan, that the reason of this was the Hebrews eating the animals which the Egyptians held sacred. To this must be added, however, that the Egyptians were addicted to such superstitious ceremonies in dressing and eating their victuals, that they could not endure to sit at table with persons of other nations. According to Herodotus, it was not only to the Hebrews that they had such an aversion, for he assures us they would not use the pots or knives of the Grecians about their food, lest these utensils should have been defiled with cutting or containing the flesh of those animals which they accounted sacred. There is some reason, notwithstanding, to think that these superstitions had not begun to prevail in Joseph's days, and that the cause of this abhorrence must be sought for in the difference of the civil rather than the religious manners of the two nations.