IMPORTANCE OF A WILL H 578 "If a Muslim has something to leave as an inheritance he should not let even two nights pass without executing a written will." R 578 Bukhari and Muslim with a chain up to Abdullah, the son of Omar who related that the Prophet, praise and peace be upon him, said this.
574- وعنه : أنَّ رسول الله صلى الله عليه وآله وسلم ، قَالَ : "مَا حَقُّ امْرِئٍ مُسْلِمٍ ، لَهُ شَيْءٌ يُوصِي فِيهِ ، يَبيتُ لَيْلَتَيْنِ إِلاَّ وَوَصِيَّتُهُ مَكْتُوبَةٌ عِنْدَهُ" متفقٌ عَلَيْهِ ، هَذَا لفظ البخاري