Thou shalt not plough with an ox and an ass together
They might be used separately, but not together; nor was it uncommon in some countries for asses to be employed in ploughing as well as oxen. Pliny F8 makes mention of some fruitful land in Africa, which when it was dry weather could not be ploughed by oxen, but after showers of rain might be ploughed by a mean little ass; so Leo Africanus F9 says, the Africans only use horses and asses in ploughing. The reason why they were not to be put together was either (as some think) lest the law should be broken which forbids the gendering of cattle with a divers kind, ( Leviticus 19:19 ) but Aben Ezra thinks the reason is, because the strength of an ass is not equal to the strength of an ox; and therefore he supposes this law is made from the mercy and commiseration of God extended to all his creatures; though perhaps the better reason is, because the one was a clean creature, and the other an unclean, and this instance is put for all others; and with which agree the Jewish canons, which run thus,
``cattle with cattle, wild beasts with wild beasts, unclean with unclean, clean with clean (i.e. these may be put together); but unclean with clean, and clean with unclean, are forbidden to plough with, to draw with, or to be led together F11.''The mystery of this is, that godly and ungodly persons are not to be yoked together in religious fellowship: see ( 2 Corinthians 6:14 ) .