Shabbat 57a and Shabbat 57b, beginning Bameh Isha, a chapter about what people can wear where there is no eruv, what counts as a garment, but more significantly what kinds of decorations we worry people (particularly women) will take off to show others, and then forget and carry them in a public place. To avoid the problem, Hazal made the rule of not wearing such items even to a hatzer, a courtyard.
