Matthew Poole and continuators on Deuteronomy 25:3

3 Forty stripes he may give him, and not exceed : lest if he should exceed, and beat him above these, with many stripes, then thy brother should seem vile unto thee .

It seems not superstition, but prudent caution, when the Iews would not exceed 39 stripes, 2 Cor. 11. 24. least through mistake or forgetfulness or eagerness they should go beyond their bounds, which they were commanded to keep, but they were not obliged to go to the utmost extent of them.

Who though faulty and chastized, yet still is thy brother by nation, and probably, by religion too.

(i. e.) Should be made contemptible to his brethren, either by this cruel usage of him as if he were a slave or brute beast: or by the desormity or infirmity of body which excessive beating might produce.

Marginal references: 2 Cor. 11. 24.