The Messenger of Allah ﷺ said: "What is the matter with people who lift their gaze to the sky when praying?" And he spoke sternly concerning that until he said: "They must stop that or they will certainly lose their eyesight."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ مَا بَالُ أَقْوَامٍ يَرْفَعُونَ أَبْصَارَهُمْ إِلَى السَّمَاءِ فِي صَلاَتِهِمْ فَاشْتَدَّ قَوْلُهُ فِي ذَلِكَ حَتَّى قَالَ لَيَنْتَهُنَّ عَنْ ذَلِكَ أَوْ لَتُخْطَفَنَّ أَبْصَارُهُمْ  

A man from among the companions of the Prophet ﷺ told him that he heard the Messenger of Allah ﷺ say: 'If any one of you in praying, let him not lift his gaze to the sky, or his eyesight will be taken away.'"  

أَنَّ رَجُلاً مِنْ أَصْحَابِ النَّبِيِّ ﷺ حَدَّثَهُ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ ﷺ يَقُولُ إِذَا كَانَ أَحَدُكُمْ فِي الصَّلاَةِ فَلاَ يَرْفَعْ بَصَرَهُ إِلَى السَّمَاءِ أَنْ يُلْتَمَعَ بَصَرُهُ