Smacking/Spanking

Firstly…apologies for my grammar as my first language is not English.
I am about to finish the “Teaching Self-government” course and started to implement what I have learnt. My husband said he is happy to watch as well and make the necessary changes but he does not believe we should stop smacking our child. He bases his opinion in Prov. 13:24 and believes disciplining sometime requires smacking. Can you help me to show biblically that this is not the best way to discipline a child and specially a child who inly 5 years old and already very oppositional, maybe because of ASD and ADHD, but since I am the one who spends most of the time with my son, I know that if I get physical with him every time he doesn’t listen or is disrespectful, I will probably spend the day hitting him and end up destroying his soul. I feel I am managing to keep calm when my son confronts me and your strategies work most of the times but some days it doesn’t matter to him if he has to do extra chores or loose his privilegies and those are the moments we feel tempted to go back to the old ways of disciplining…threatening, raising the voice or smacking.