Deuteronomy 22:10 KJV

Thou shalt not plow with an ox and an ass together.
Deuteronomy 22:10, King James Version

In 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.