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. (Using translation from Abū Dāʾūd 2862)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ مَا حَقُّ امْرِئٍ مُسْلِمٍ لَهُ شَيْءٌ يُوصِي فِيهِ يَبِيتُ لَيْلَتَيْنِ إِلَّا وَوَصِيَّتُهُ عِنْدَهُ مَكْتُوبَةٌ