John Wesley on Deuteronomy 25:3

Forty stripes - It seems not superstition, but prudent caution, when the Jews would not exceed thirty - nine stripes, lest through mistake or forgetfulness they should go beyond their bounds, which they were commanded to keep. Should seem vile - Should be made contemptible to his brethren, either by this cruel usage of him, as if he were a brute beast: or by the deformity or infirmity of body which excessive beating might produce.