Is the waiting period (iddah) obligatory for a woman who left her husband's home and filed for annulment of the marriage, and is it permissible for her to adorn herself in her family's home during the waiting period, and does she sin if she does not observe the waiting period?

The default is that a wife should not leave her husband's house without his permission, and requesting a divorce without a valid reason is forbidden, based on the Prophet's (peace be upon him) saying: "Any woman who asks her husband for a divorce without any harm (afflicting her), the scent of Paradise will be forbidden for her." However, she is permitted to request a divorce if she is harmed by remaining with her husband or fears that she will not be able to uphold Allah's limits concerning him, as stated by Ibn Qudamah.

The 'iddah (waiting period) only begins after the divorce has occurred, either by the husband's pronouncement or by a judge's ruling. It commences from the moment it takes place, even if the woman is far from her husband. It is a right due to Allah the Almighty and a respect for the marriage contract.

If the divorce is revocable (raj'i), the wife must observe her 'iddah in her husband's house, and she is permitted to adorn herself for him. As for an irrevocable divorce (ba'in), there is a difference of opinion regarding the necessity of observing mourning (ihdad). Any divorce ruled by a judge is typically irrevocable.