It is hard, but it is excellent, to find the right knowledge of when correction is necessary and when grace doth most avail.
I was in prison, and you came unto me. Verily I say unto you, inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me.
~(Jesus Christ) Matthew 25:36, 40
A just chastisement may benefit a man, though it seldom does; but an unjust one changes all his blood to gall.
Justice is justice though it's always delayed and finally done only by mistake.