People dress for a number of reasons:
- To cover themselves
- To keep warm
- To feel and look smart
All these reasons are fine, but some people dress to show off and to look attractive so that other people can stare at them. This is not right since you are using the clothes to make other people gaze at your body.
"If a person dresses up and prides himself over others by because of his clothes, a flame of hell overtakes him, and he will swing in it until the day of Judgement."
This means that he will be punished partly in this life (i.e. part of hell in this life). The punishment can be no friends, or no happiness, no satisfaction.
Your body is precious and private. It has been lent to you from Allah is yours to look after. You should not abuse it, and you should not use it as a show for others. You see, if something is expensive and important, it will be guarded and kept away so that people don't use it and damage it, but if something is cheap, it will be left there for everybody to see and use, and no one will care about it. What is more precious than your body? To ensure that you guard its respect you dress in such a way that it is not exposed more than necessary.
When you dress, you should make sure that the clothes you wear are not so tight that the shape of your body is seen. Also you should be careful not to wear certain clothes to certain places.
You would not wear jeans if you were invited to see the Queen, so why wear jeans when you go to the mosque, to be closer to Allah?
You can wear jeans at home or when you go out, but you should try and avoid them in places like the mosque. This is simply because there is a certain respect attached with certain clothes.
Even at home, you should make sure that you are dressed properly. It is very poor Akhlaq to walk around the home without a shirt, or to walk around wearing only your underwear or boxer shorts. It may sound funny, but many people do this.
If you start to treat your own body as cheap, then don't complain when others also treat you as if you were cheap and worthless.