C. F. Keil and Franz Delitzsch on Genesis 43:32-34

Gen 43:32-33

Separate tables were prepared for him, for his brethren, and for the Egyptians who dined with them. This was required by the Egyptian spirit of caste, which neither allowed Joseph, as minister of state and a member of the priestly order, to eat along with Egyptians who were below him, nor the latter along with the Hebrews as foreigners. “They cannot (i.e., may not) eat (cf. Deu 12:17; Deu 16:5; Deu 17:15). For this was an abomination to the Egyptians.” The Hebrews and others, for example, slaughtered and ate animals, even female animals, which were regarded by the Egyptians as sacred; so that, according to Herod. ii. 41, no Egyptian would use the knife, or fork, or saucepan of a Greek, nor would any eat of the flesh of a clean animal which had been cut up with a Grecian knife (cf. Exo 8:22).