The concession allowing praying behind one who is sleeping

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"

أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ هِشَامٍ، قَالَ حَدَّثَنَا أَبِي، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ وَأَنَا رَاقِدَةٌ مُعْتَرِضَةٌ بَيْنَهُ وَبَيْنَ الْقِبْلَةِ عَلَى فِرَاشِهِ فَإِذَا أَرَادَ أَنْ يُوتِرَ أَيْقَظَنِي فَأَوْتَرْتُ .