Deuteronômio 22:10 Comentário: Rashi, Chizkuni, Da'at Zekenim & Ramban

לא תחרש בשור ובחמור THOU SHALT NOT PLOUGH WITH AN OX AND WITH AN ASS [TOGETHER] — The same law applies to any two different kinds of animals in existence; the same law applies also to merely driving them together (when not ploughing) whilst they are yoked together as a pair carrying any load (Sifrei Devarim 232:1-2; cf. Kilayim 8:2 and 3; Bava Metzia 8b).

לא תחרוש בשור וחמור, “do not plough with an ox and donkey together pulling the plough.” The ox, being an animal that chews the cud is constantly eating, whereas the donkey in the meantime is being overworked. This is an example of inflicting pain on living creatures. (Baaley Tossaphot.) Another explanation is that the ox is considered to be the king of the domesticated animals and his image is engraved on the Divine Throne, while the donkey is considered to be a despicable animal. This is not a befitting union. An alternate interpretation; G-d’s mercy extends not only to human beings but to all of His creatures. Therefore these two categories of beasts being mismatched as one is far stronger than the other, it would be causing the donkey pain to be part of such a team pulling the plough.

לא תחרוש בשור ובחמור יחדיו, “You shall not plough with and ox and a donkey together.” The ox is a pure species chewing the cud, whereas the donkey is an impure species. When the donkey hears the ox chewing food it pains him. [Apparently, chewing the cud is a noisy procedure. Ed.]