Usamah bin Zaid (radi Allahu anhu) narrated: “The Messenger of Allah (sal Allahu alaihi wa sallam) gave me a relatively thick piece of material known as Qibtiyah which was presented to him by Dahyah al-Kalbi. I gave that material to my wife. The Messenger of Allah (sal Allahu alaihi wa sallam) asked me, ‘How come you did not wear the Qibtiyah?’ I replied, ‘O Messenger of Allah! I gave it to my wife for her dress.’ He said, ‘Ask her to make a lining for it; I am afraid (because of its being quite thin) it may outline the frame of her body.’” [Musnad Ahmad]
On another occasion, some women from the tribe of Banu Tameem came to visit Aisha (radi Allahu anha). They were wearing dresses made of very thin material. When Aisha (radi Allahu anha) saw them she said, “If you are Mumin, this is not a type of dress suitable for Mumin women. But if you are not Mumin, then do as you please.” [Tafseer Qurtubi, vol. 14, p. 244]
Am I a Mumin?