كتاب الوصايا
Read the English translation first, with the original Arabic directly underneath.
Narrated `Abdullah bin `Umar:
Allah's Messenger (ﷺ) said, "It is not permissible for any Muslim who has something to will to stay for two nights without having his last will and testament written and kept ready with him."
مَا حَقُّ امْرِئٍ مُسْلِمٍ لَهُ شَىْءٌ، يُوصِي فِيهِ يَبِيتُ لَيْلَتَيْنِ، إِلاَّ وَوَصِيَّتُهُ مَكْتُوبَةٌ عِنْدَهُ