Notice that this proverb speaks of both “rod” and “reproof.” These are the two disciplinary measures given to parents. They should both be used with love and discernment (see Ephesians 6:4). Without such discipline a child is “left to himself,” with nothing to guide him through life but his own evil inclinations (Genesis 8:21).
15 The rod and reproof give wisdom, but a child left to himself brings shame to his mother.