The Messenger of Allah ﷺ as saying: It is the duty of a Muslim man who has something which is to be given as bequest not to have it for two nights without having his will written regarding it.  

عَنْ رَسُولِ اللَّهِ ﷺ قَالَ مَا حَقُّ امْرِئٍ مُسْلِمٍ لَهُ شَىْءٌ يُوصِي فِيهِ يَبِيتُ لَيْلَتَيْنِ إِلاَّ وَوَصِيَّتُهُ مَكْتُوبَةٌ عِنْدَهُ  

The Messenger of Allah ﷺ did not leave dinars, dirhams, camels and goats, nor did he leave will for anything.  

مَا تَرَكَ رَسُولُ اللَّهِ ﷺ دِينَارًا وَلاَ دِرْهَمًا وَلاَ بَعِيرًا وَلاَ شَاةً وَلاَ أَوْصَى بِشَىْءٍ