Seeing a woman in a state of mourning who is uncovered does not invalidate the mourning period

Question: If a man sees a woman who is uncovered without intending to, and she is in the period of mourning for a deceased person—her husband—what does this entail for her? Does she have to repeat the mourning period?

Answer: If a man sees a woman who is uncovered, he must lower his gaze and turn it away from her. The Prophet (peace and blessings be upon him) was asked about the sudden glance, and he said: , and he said: .
The meaning is that there is no blame on him for the first glance, which was accidental and not intended, when he happened to encounter her at a doorway or similar place while he was inside, or on the road. He should turn his gaze away and not follow the glance with another; rather, he must lower his gaze.
As for the woman in mourning and other women, nothing is required of her in this matter if she does not follow the glance with another; rather, she should cover herself and observe seclusion. She does not have to repeat the mourning that has already passed; rather, she continues in her mourning and nothing is required of her.
However, she is obligated to stay away from the causes of fitnah (trial, discord or temptation) and to observe seclusion from non-mahram men, just like other women, without distinction. This is not specific to the woman in mourning or others, but she—like other women—must observe seclusion and stay away from the causes of fitnah.
And a woman in the waiting period must observe five matters:
1 - Residing in the house where her husband died, in which she is living, if it is suitable for her to remain in it. However, if it is not feasible for her to stay in it due to its dilapidation, or because his family refused to rent it to her when the lease term ended, or because she has no one to keep her company in it after her husband's death and she fears for her safety, then she should move to her family or to a safe place.
2 - She must wear ordinary clothes, not clothes that cause fitnah. She should not wear beautiful clothes, but rather seek out clothes that do not cause fitnah, such as ordinary black, green, or other colors, provided they contain nothing that causes fitnah for people.
3 - Avoiding jewelry made of gold, silver, diamonds, and the like.
4 - Not using perfume, incense, or other types of fragrance; because the Messenger (peace and blessings be upon him) forbade the woman in mourning from doing so, except when she is purified from her menstruation, in which case she may use some perfume.
5 - Not using kohl, henna, or the like; because these are also causes of fitnah. These five matters are prescribed for the woman in mourning to attend to; because the Prophet (peace and blessings be upon him) commanded them, so it is obligatory for her to do so.
As for everything else, she is like the rest of the women; she may take a full ritual bath and wash her hair whenever she wishes—on Friday and other days—and she may change her clothes whenever she wishes. She may speak directly to any woman or man she wishes, or by telephone, or by correspondence, and there is no blame in that, provided the conversation contains no fitnah or suspicion. Rather, she speaks for her need, returns the greeting to those who greet her, and the like, in a manner that contains no fitnah and no shubhah (a doubtful matter).