What is the ruling on baring one's rear for one's father to strike it?

What is between the navel and the knee for someone who has reached twelve years of age is considered 'awrah (private parts) and it is not permissible to touch it or look at it. The 'awrah of a child who has reached ten years of age is like the 'awrah of adults, from the navel to the knee. Therefore, it was not permissible for the father to order the exposure of the 'awrah at that age.