Deuteronomy 22:10 in the King James Version
Thou shalt not plow with an ox and an ass together.
Context
9 You shall not sow your vineyard with two kinds of seed, lest all the fruit be defiled, the seed which you have sown, and the increase of the vineyard.
10 You shall not plow with an ox and a donkey together.
11 You shall not wear clothes of wool and linen woven together.