"It is not permissible for a woman who believes in Allah and the Last Day, to mourn for anyone who dies for more than three days, except for a husband; she should not use kohl, dye nor wear dyed clothes." (Using translation from Nasāʾī 3536)  

عَنِ النَّبِيِّ ﷺ قَالَ «لَا يَحِلُّ لِامْرَأَةٍ تُؤْمِنُ بِاللهِ وَالْيَوْمِ الْآخِرِ أَنْ تُحِدَّ عَلَى مَيِّتٍ فَوْقَ ثَلَاثٍ إِلَّا عَلَى زَوْجٍ وَلَا تَكْتَحِلُ وَلَا تَخْتَضِبُ وَلَا تَلْبَسُ ثَوْبًا مَصْبُوغًا»