Hadith: When a woman’s husband died, she would go into a small hut, wear her worst clothes and would not touch any kind of perfume until a whole year would pass. Then an animal – a donkey, bird, or sheep – would be brought to her and she would rub her skin with it

عن أم سلمة رضي الله عنها مرفوعاً: «جاءت امرأة إلى رسول الله صلى الله عليه وسلم فقالت: يا رسول الله، إن ابنتي توفي عنها زوجها، وقد اشتكت عينها أفَنَكْحُلُها؟ فقال رسول الله صلى الله عليه وسلم : لا -مرتين، أو ثلاثا-، ثم قال: إنما هي أربعة أشهر وعشر، وقد كانت إحداكن في الجاهلية ترمي بالبَعْرَةِ على رأس الحول». فقالت زينب: كانت المرأة إذا توفي عنها زوجها: دخلت حفشا، ولبست شر ثيابها، ولم تَمَسَّ طيبا ولا شيئا حتى تمر بها سنة، ثم تؤتى بدابة -حمار أو طير أو شاة- فتَفْتَضُّ به! فقلما تفتض بشيء إلا مات! ثم تخرج فتُعطى بعرة؛ فترمي بها، ثم تراجع بعد ما شاءت من طيب أو غيره».
[صحيح] - [متفق عليه]

Umm Salamah (may Allah be pleased with her) reported: A woman came to the Messenger of Allah (may Allah's peace and blessings be upon him) and said: "O Messenger of Allah, my daughter’s husband died, and she complains about her eye. Can we apply Kohl thereto?" The Messenger of Allah (may Allah's peace and blessings be upon him) said 'No' twice or thrice. Then he said: "It is only four months and ten days. In the pre-Islamic era, you women would throw away the dung after a year had passed." Zaynab said: “When a woman’s husband died, she would go into a small hut, wear her worst clothes and would not touch any kind of perfume until a whole year would pass. Then an animal – a donkey, bird, or sheep – would be brought to her and she would rub her skin with it. It was seldom that she would rub her skin with any animal except that it died! Then she would come out and be given a piece of dung, which she would throw away. Then, she would return to using perfume or anything else she liked.”
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

Islam came and relieved people of the hardship of the pre-Islamic era, especially the woman, who was mistreated and wronged but Islam preserved her rights. In this Hadīth, a woman came seeking a legal ruling from the Prophet (may Allah's peace and blessings be upon him) as she told him that her daughter’s husband had died and that her daughter was in her mourning period, during which she had to abstain from adornment. However, she complained about some pain in her eyes. The woman asked whether there was a concession allowing her daughter to use Kohl. The Prophet (may Allah's peace and blessings be upon him) said: "No", repeating it in confirmation of his disapproval. Then he made a remark about the considerable shortness of the duration of a widow’s period of mourning as a veneration of the husband, which is four months and ten days. Then he wondered why women would not endure this short period that involved ease and comfort? In the pre-Islamic era, a widow would observe the mourning period in a small house, like a den in the wilderness, and for a full year she would abstain from adornment, perfume, water, and mixing with people, such that the filth and dirt would accumulate on her body, while being secluded from people. When her mourning period ended, she would be given a piece of dung, which she would then throw away, as an indication that what she went through of confinement, hardship and difficulty is as insignificant as that piece of dung when compared to her husband's huge right upon her. When Islam came, it replaced such a distress with favor, and such a difficulty with ease. However, women were too impatient to refrain from applying Kohl to their eyes. That is why no concession was granted to such a woman in this case, in order not to be a means leading to allowing adornment for a woman in her mourning period.