Deuteronomy 22:10 in the World English Bible
You shall not plow with an ox and a donkey together.
Context
9 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.
10 Thou shalt not plow with an ox and an ass together.
11 Thou shalt not wear a garment of divers sorts, as of woollen and linen together.