Is the fast of one who remains in a state of janabah from night until Maghrib, and does not purify himself, valid, and is it permissible to describe a person in a state of janabah as najis, and a menstruating woman or a woman in postpartum bleeding as najisah?

If a fasting person becomes in a state of ritual impurity (junub), their fast is valid because purity is not a condition for its validity. It is permissible to delay the ritual bath (ghusl) until after Fajr (dawn) prayer. However, it is not permissible to deliberately delay the ghusl and miss prayers. Furthermore, it is impermissible to describe a Muslim as impure, whether they are in a state of janabah, menstruation, or post-childbirth bleeding (nifas), based on the Almighty's saying: ﴿Indeed, the polytheists are impure﴾ [Quran 9:28], and the Prophet’s (peace be upon him) saying: "Indeed, a believer does not become impure."