What is the ruling on applying nail polish during menstruation and at other times? Are there any authentic Prophetic narrations regarding this?

The Sharia has permitted women to adorn themselves with nail polish if it is pure and not harmful. However, since nail polish has a substance that prevents water from reaching the skin, it must be removed before performing ablution (Wudu') or ritual bath (Ghusl). If it has a substance, it must be removed so that it does not prevent water from reaching the nail. As for things that do not have a substance, like henna, they do not cause harm. There is no objection for a menstruating woman, who does not pray, to use it, and she should remove it when performing the ritual bath. No specific hadith has been reported regarding nail polish; it falls under the general principle that the default ruling for pure and non-harmful things is permissibility.