The Qur'an tells both women and men to be modest. [For some Muslims, modest clothing for women is a head covering called a 'hijab', but this was not worn in all medieval Muslim societies. Whenever a woman entered a mosque, however, she would always have her head covered. (This was also true of medieval Christian women entering a church.) In some societies even the woman's face was covered.] The Qur'an tells men that they should not wear silk or gold jewelry to show off their wealth. Clothing should not attract attention or be worn to show off. Clothing must cover the entire body; only the hands and face may remain visible. The material must not be so thin that one can see through it. Clothing must hang loose so that the shape of the body is not shown off. The woman's clothing must not resemble the man's clothing, nor should the man's clothing resemble the woman's. Women shouldn't artificially lengthen their hair with wigs or weaves, nor have tattoos. A Muslim should not wear clothing to look like a non-Muslim. (For example, the Persians were known for wearing red, many silk robes, and their men's robes had long trains which dragged behind them. The Prophet Muhammad was against Muslims copying these styles.) Men's robes or shirts should extend down from halfway below the shin but over the ankles, but not so long as to trail behind on the ground. While praying in a mosque, clothing should be plain and not be distracting. A man's hair might be criticized if it was shoulder-length or longer. The Prophet Muhammad preferred men to wear their hair neat and cut a little below the ears.