عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ: ((لَا يَحِلُّ لِامْرَأَةٍ تُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الْآخِرِ أَنْ تُحِدَّ عَلَى مَيِّتٍ فَوْقَ ثَلَاثٍ، إِلَّا عَلَى زَوْجٍ))
It is narrated from Sayyidah Aisha (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: It is not permissible for a woman who believes in Allah and the Last Day to mourn for any deceased person for more than three days, except for her husband.