ANSWER: The New Testament Bible verse regarding child abuse that quickly comes to mind is in Colossians 2. The same admonition is repeated in Paul's book of Ephesians, chapter 6 and verse four.
Parents, do not irritate (the NKJV and other translations have "provoke") your children, or they will become discouraged. (Colossians 3:21)
Both of these are addressed to the fathers in the household and, by extension, to anyone in authority over that child. Those in authority are commanded, not suggested, to not provoke (abuse) them until he or she becomes violently angry or in a rage of frustration.
If a child is provoked, even for his own good (as some would argue), this is permitted but that is not what God demands. So I would have to say from these two scriptures that people in authority should not abuse these blessings from God for any reason.
Another place that might be of help to understand our Father's loving mind toward children and how to treat them is the admonition to not even put barriers before "little ones" (see Matthew 18:1 - 6 and Mark 9). Clearly, Jesus takes the abuse or hindering, etc. of children, especially those who are spiritually quite young, VERY seriously! As parents we must always teach in love and discipline with justice - and not abuse. This does not mean an adult should be passive and not correct a child for bad and unacceptable behavior because that too is a sign of being unloving and abusive. Even God, because of his perfect love, chastens or corrects those he has received as children (Hebrews 12:7, Revelation 3:19).
One of the primary problems for each generation is to figure out what IS abuse. In the modern English dictionaries the definition is to attack verbally, to misuse or mistreat someone. This can be manifested in verbal insults, physical battery (although spanking done in love and for the good of the child is permitted), emotional and psychological mistreatment because of lies and hypocrisy, and spiritual deception.
The first lesson of mankind outside the garden, found in the story of Cain and Abel, is that we are not to murder brother. The Bible is full of stories of humans abusing each other. God certainly does not like this behavior amongst his own children (us) and would never approve of abuse for any reason. He is a Being of law and order. He is Love and Truth and Mercy.
In conclusion, the Bible clearly states that we should NEVER condone or be a part of child abuse or any other kind of abuse against our fellow men and women, regardless of their age. Such attitudes and actions come from the "works of the flesh," our human nature apart from God, which Paul enumerates in Galatians (Galatians 5:14-15, 19-21).
I hope this brief explanation about what the Bible says about child abuse spurs you on to further study this topic in scripture. In the end, please remember that God holds us responsible for teaching our offspring his ways (Deuteronomy 4:9).