"A woman came to the Prophet and said: 'My daughter's husband has died, and I am worried about her eyes. Can I apply kohl to her?' The Messenger of Allah said: 'One of you used to stay (in mourning) for a year. Rather (the mourning period is) four months and ten (days). And when that year had passed she would go out and fling a piece of dung behind her.'" (Using translation from Nasāʾī 3502)  

عَنْ يَحْيَى بْنِ سَعِيدِ بْنِ قَيْسِ بْنِ قَهْدٍ الْأَنْصَارِيِّ وَجَدُّهُ قَدْ أَدْرَكَ النَّبِيَّ ﷺ عَنْ حُمَيْدِ بْنِ نَافِعٍ عَنْ زَيْنَبَ بِنْتِ أُمِّ سَلَمَةَ عَنْ أُمِّ سَلَمَةَ وَأَمِّ حَبِيبَةَ قَالَتَا جَاءَتِ امْرَأَةٌ إِلَى النَّبِيِّ ﷺ فَقَالَتْ إِنَّ ابْنَتِي تُوُفِّيَ عَنْهَا زَوْجُهَا وَإِنِّي أَخَافُ عَلَى عَيْنِهَا أَفَأَكْحُلُهَا؟ فَقَالَ رَسُولُ اللهِ ﷺ «قَدْ كَانَتْ إِحْدَاكُنَّ تَجْلِسُ حَوْلًا وَإِنَّمَا هِيَ أَرْبَعَةُ أَشْهُرٍ وَعَشْرًا فَإِذَا كَانَ الْحَوْلُ خَرَجَتْ وَرَمَتْ وَرَاءَهَا بِبَعَرَةٍ»