"The Messenger of Allah ﷺ said: 'If a man feels drowsy when he is praying, let him stop, lest he supplicate against himself without realizing.'" (Using translation from Nasāʾī 162)  

قَالَ رَسُولُ اللهِ ﷺ «إِذَا نَعَسَ الرَّجُلُ وَهُوَ يُصَلِّي فَلْيَنْصَرِفْ لَعَلَّهُ يَدْعُو عَلَى نَفْسِهِ وَهُوَ لَا يَدْرِي»  

"If anyone of you feels drowsy during his Salah, let him go and take a nap." (Using translation from Nasāʾī 443)   

عَنِ النَّبِيِّ ﷺ قَالَ «إِذَا نَعِسَ أَحَدُكُمْ فِي صَلَاتِهِ فَلْيَنْصِرِفْ فَلْيَنَمْ»