What is the lesson behind the law against plowing with an ox and a donkey together?
Deuteronomy 22:9's prohibition taught the unequal-yoke lesson: pairing animals of unequal strength is ridiculous and unworkable. God used it to teach His people not to mix things that cannot work together, because an unequal yoking produces an absurd, out-of-harmony situation, as illustrated by the ox and the little donkey.
Les explains that Deuteronomy 22:9 says, “Thou shalt not plow out in the field with an ox and an ass or a little donkey together.” He asks us to picture it: the poor little donkey would be working his tail off to keep up with the big ox, and it is ridiculous. He points out that the Jewish people probably were not actually doing this, so the command was not chiefly about their current practice. Rather, the lesson it taught is that as soon as you have an unequal yoke, you have something ridiculous. An ox and a little donkey are as ridiculous as you can get—simply an unequal yoking. Les connects this to the next law, which forbids making a garment part wool and part linen. When such a garment was washed, it would become contorted, out of shape, and look ridiculous. Again, many Jews likely did not try to make such garments, but God was teaching a lesson: don’t mix things that won’t work together. That is the simple lesson.
Thou shalt not sow thy vineyard with divers seeds: lest the fruit of thy seed which thou hast sown, and the fruit of thy vineyard, be defiled.