Folding up sleeves or trousers?

Q: Is it permissible to play sports with another person who is wearing shorts?

A: It is not permissible to play sports with a person wearing shorts. They may reveal some of his `Awrah (parts of the body that must be covered in public) and for fear of sexual excitement. Men's `Awrah is the area between the navel and the knees.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.