Sahih Muslim Book - 18, Hadith - 3728

قَالَ حُمَيْدٌ قُلْتُ لِزَيْنَبَ وَمَا تَرْمِى بِالْبَعَرَةِ عَلَى رَأْسِ الْحَوْلِ فَقَالَتْ زَيْنَبُ كَانَتِ الْمَرْأَةُ إِذَا تُوُفِّىَ عَنْهَا زَوْجُهَا دَخَلَتْ حِفْشًا وَلَبِسَتْ شَرَّ ثِيَابِهَا وَلَمْ تَمَسَّ طِيبًا وَلاَ شَيْئًا حَتَّى تَمُرَّ بِهَا سَنَةٌ ثُمَّ تُؤْتَى بِدَابَّةٍ حِمَارٍ أَوْ شَاةٍ أَوْ طَيْرٍ فَتَفْتَضُّ بِهِ فَقَلَّمَا تَفْتَضُّ بِشَىْءٍ إِلاَّ مَاتَ ثُمَّ تَخْرُجُ فَتُعْطَى بَعَرَةً فَتَرْمِى بِهَا ثُمَّ تُرَاجِعُ بَعْدُ مَا شَاءَتْ مِنْ طِيبٍ أَوْ غَيْرِهِ.

Humaid said: "I said to Zainab: 'What is this throwing a piece of dung at the end of one year? Zainab said: 'If a woman's husband died, she would go into a hut and wear her worst clothes, and she would not put on perfume or anything until one year had passed. Then an animal would be brought - a donkey or a sheep or a bird - she would rub her hands over it, and rarely did (such a woman) rub her hands over anything but it died. Then she would be given a piece of dung which she would throw, then she would go back to whatever she wanted to of perfume and other things."'