And it prohibits an ox and ass to be yoked in the plough together; pointing perhaps to the want of agreement in the case of the animals; and at the same time teaching not to wrong any one belonging to another race, and bring him under the yoke, when there is no other cause to allege than difference of race, which is no cause at all, being neither wickedness nor the effect of wickedness.
Clement of Alexandria
The Stromata, Book II
Chapter XVIII