The concession allowing praying behind one who is sleeping Sunan an-Nasa'i 759
Arabic hadith text
أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ هِشَامٍ، قَالَ حَدَّثَنَا أَبِي، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلميُصَلِّي مِنَ اللَّيْلِ وَأَنَا رَاقِدَةٌ مُعْتَرِضَةٌ بَيْنَهُ وَبَيْنَ الْقِبْلَةِ عَلَى فِرَاشِهِ فَإِذَا أَرَادَ أَنْ يُوتِرَ أَيْقَظَنِي فَأَوْتَرْتُ .
Translation
It was narrated that Aisha said
"The Messenger of Allah(ﷺ)used to pray at night while I was lying down sleeping between him and the Qibla on his bed. When he wanted to pray witr he would wake me up and I would pray witr"