"The Messenger of Allah ﷺ said: 'When any one of you gets up after (sleeping) at night, let him not put his hand into the vessel until he has poured water on it two or three times, for none of you knows where his hand spent the night.'"  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا قَامَ أَحَدُكُمْ مِنَ اللَّيْلِ فَلاَ يُدْخِلْ يَدَهُ فِي الإِنَاءِ حَتَّى يُفْرِغَ عَلَيْهَا مَرَّتَيْنِ أَوْ ثَلاَثًا فَإِنَّ أَحَدَكُمْ لاَ يَدْرِي أَيْنَ بَاتَتْ يَدُهُ  

"I prayed with the Prophet ﷺ one night, and I stood on his left, but he made me stand on his right, and he prayed. Then he reclined on his side and took a nap, then the Mu'adhdhin came to him and he prayed, and did not perform Wudu'."  

صَلَّيْتُ مَعَ النَّبِيِّ ﷺ ذَاتَ لَيْلَةٍ فَقُمْتُ عَنْ يَسَارِهِ فَجَعَلَنِي عَنْ يَمِينِهِ فَصَلَّى ثُمَّ اضْطَجَعَ وَرَقَدَ فَجَاءَهُ الْمُؤَذِّنُ فَصَلَّى وَلَمْ يَتَوَضَّأْ مُخْتَصَرٌ  

"If anyone of you feels drowsy during his Salah, let him go and take a nap."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا نَعَسَ أَحَدُكُمْ فِي صَلاَتِهِ فَلْيَنْصَرِفْ وَلْيَرْقُدْ