Although this can be read by itself, it is recommend to read "Words That Parents Shouldn't Speak To Their Kids" first to get an understanding of the complete subject.

A statement parents should not say to their kids is "Why can't you act more mature"? Kids want to feel that they have accomplished something, to feel sure and capable of doing something right. Kids will make mistakes because they are learning new things. It is not wise to judge kids as "big babies" or childish just because they drop a glass of drink or wet the bed on occasion. Such remarks can only cause nervousness and embarrassment. Fear of disappointment from a parent because a child has made a mistake will only cause more mistakes to happen. A child should be able to receive a sense of achievement from their parents in learning a new thing. A parent should give praise to their children when they can go to the potty by themselves or can drink from a "big cup" now. If a child needs to be corrected, turn a negative into a positive. For example, when a child drops their cup and their drink spills don't say "Why can't you act more grown up" but say "You dropped your drink. Since you are a big girl/boy now, I know you'll be able to hold you drink without spilling on the next try".

Another statement a parent shouldn't say to a child is "I was only kidding with you". A parent may think it's their job to tease their kids at home to prepare them for the possible teasing they would receive from the outside world. This concept doesn't work. Teasing from a parent can feel like embarrassment to young children. A parent wouldn't beat up their kids at home as a way to prepare them for fights on the playground. A parent's job is to provide a safe haven from the world and to love them. The world can toughen kids up in its own time.

Another statement a parent shouldn't say is "My child is always good and never does a bad thing". This way of thinking is not fair to the child. Even children can have competitive and angry feelings. Parents should let kids have a range of both positive as well as negative feelings. To not be allowed this is not praise but manipulation. A better way to give proper praise (or criticism for that matter) is to point out the behavior and not the child. Say "What you did was great" instead of "You're such a good boy/girl".

Another statement a parent shouldn't say is "I'll do it myself, you're too slow". A child will feel that they can't do anything right if parents have this attitude. Parents should resist the urge to do things for their kids especially when the kids are old enough to do it themselves like put on their shoes or pick up their toys. It will leave the kids with the idea of why do something, my parents will just do it for me so I won't have to.

What a parent SHOULD say to a child? "I'm sorry" if they say something cruel or do something wrong to their children. Parents may think this takes away from their authority if they apologize to their children. Children deserve respect just as adults do. Get to the point and say you're sorry and didn't mean to and even if you said or did something wrong, let them know you still love them.