Jerry Bridges, Trusting God, 1988, p. 121.
The author of Hebrews readily admits that discipline is painful (Heb. 10:11). But He also assures us it is profitable. It produces “a harvest of righteousness and peace.” The purpose of God’s discipline is not to punish us but to transform us. He has already meted out punishment for our sins on Jesus at Calvary: “The punishment that brought us peace was upon Him” (Isaiah 53:5). But we must be transformed more and more into the likeness of Christ. That is the purpose of discipline.
Jerry Bridges, Trusting God, 1988, p. 121.