Mishkat al-Masabih 4 Prayer كتاب الصلاة 660

وَعَنْ عَائِشَةَ قَالَتْ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا نَعَسَ أَحَدُكُمْ وَهُوَ يُصَلِّي فَلْيَرْقُدْ حَتَّى يَذْهَبَ عَنْهُ النَّوْمُ فَإِنَّ أَحَدَكُمْ إِذَا صَلَّى وَهُوَ نَاعِسٌ لَا يدْرِي لَعَلَّه يسْتَغْفر فيسب نَفسه»

‘A’isha reported God’s Messenger as saying, “When one of you dozes while praying he should fall over till he has slept enough, for when one of you prays while dozing he does not know whether he may be asking pardon and vilifying himself. (Bukhari and Muslim.)