It was narrated from Ibn 'Umar that the Messenger of Allah ﷺ said:
“The Muslim man has no right to spend two nights, if he has something for which a will should be made, without having a written will with him.”

حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " مَا حَقُّ امْرِئٍ مُسْلِمٍ أَنْ يَبِيتَ لَيْلَتَيْنِ وَلَهُ شَىْءٌ يُوصِي فِيهِ إِلاَّ وَوَصِيَّتُهُ مَكْتُوبَةٌ عِنْدَهُ " .