Now no chastening seemeth for the present to be joyous, but grievous (literally, not of joy, but of grief): nevertheless afterward it yieldeth the peaceable fruit of righteousness to them which have been exercised thereby.
This is a general statement with respect to all chastening, though the expression of its result at the end of the verse is suggested by the thought of Divine chastening, to which alone it is certainly, and in the full sense of the words, applicable.
"Of righteousness" is a genitive of apposition; δικαιοσύνη is the peaceable fruit yielded by παιδεία. And the word here surely denotes actual righteousness in ourselves; not merely justification in what is called the forensic sense: the proper effect of chastening is to make us good, and so at peace with our own conscience and with God.
It is by no means thus implied that we can be accepted and so have peace on the ground of our own imperfect righteousness; only that it is in the fruits of faith perfected by discipline that we may "know that we are of the truth, and assure our hearts before him" (cf.
James 3:18, "The fruit of righteousness is sown in peace;" also Isaiah 32:17, "And the work of righteousness shall be peace").