What is the rod of correction

 Many people misunderstand the rod of correction, and then think spanking a child is okay based on the existence of an instrument of legal correction. That's what the "correction" means here. Think Department of Corrections, and it is the same tense, same use of the word.

There are references to the rod of correction that have nothing to do with children in Proverbs. It says in Proverbs 20:30 KJV:

The blueness of a wound cleanseth away evil: so do stripes the inward parts of the belly.

This does not refer to teaching children discipline. Notice not one word referencing children in this verse. This verse was intended as a law enforcement warning that if you step too close to uncleanliness, meaning sin, you get a good whipping. 

These whippings were never imposed on children at all, and in reality, were rare. The rod of correction was a legend, meaning that if you mess up bad enough, you get that type of treatment from the court, and from then on you are marked for death upon your next offense. You had many warnings, and you ignored all of them, and so the law was fair, and you were not by your actions which hurt others, and brought shame upon the family.

Ultimately, corporal punishment in the biblical context did exist, but as judicial corporal punishment. The legal system was not like today, where you could simply summon a police officer. The parents of a delinquent adult son had to seek out help, warning him many times of his fate. It was a search party of the lamppost variety that gathered witnesses, and then put the errant son on trial. Every single parent in the history of ancient Israel who did this felt strong pressure from the family and community defending the errant son, with his behaviors being seen as mimicking an abuser - they all recanted the charges, many times of abuse of parents. It says in Colossians 3:21 KJV:

Fathers, provoke not your children to anger, lest they become discouraged.

The Greek root word translated "provoke...to anger" is ερεθιζο (Latin: erethizo) and literally translates to "stir up" and refers to legal damages against a child, meaning the slightest of personal slights perceived by the child, imposed out of willfulness or recklessness. This commandment in particular was intended to repeal the parent protection laws, stating that children act as mirrors towards parental behavior, with discouragement being them acting like you, towards you, in terms of anger and resentment. Whatever you give to your child is what you will get back.

The depraved, entitled parents who provoke children to anger will DIE in a hail of fire and brimstone, suffering the second death! Repent, for the Kingdom of Heaven is at hand!