There is no Scripture to back this up. There is, however, no reason why people should not dress up when gathering with the local believers for worship. A lot of this is based on custom. People in America used to get dressed up nearly anytime they went to a public event. Just look at old photos of Babe Ruth playing baseball. You will see that everyone watching the game is wearing a coat and tie. The main point is, we should not be condemning of those who do not dress up. The most important thing is not how nice a dress is, but how modest it is.