Sahih al-Bukhari 750
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · Looking towards the sky during As-Salat (the prayer)
Narrated Anas bin Malik:
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ ، قَالَ أَخْبَرَنَا يَحْيَى بْنُ سَعِيدٍ ، قَالَ حَدَّثَنَا ابْنُ أَبِي عَرُوبَةَ ، قَالَ حَدَّثَنَا قَتَادَةُ ، أَنَّ أَنَسَ بْنَ مَالِكٍ ، حَدَّثَهُمْ قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " مَا بَالُ أَقْوَامٍ يَرْفَعُونَ أَبْصَارَهُمْ إِلَى السَّمَاءِ فِي صَلاَتِهِمْ ". فَاشْتَدَّ قَوْلُهُ فِي ذَلِكَ حَتَّى قَالَ " لَيَنْتَهُنَّ عَنْ ذَلِكَ أَوْ لَتُخْطَفَنَّ أَبْصَارُهُمْ " .
The Prophet (ﷺ) said, "What is wrong with those people who look towards the sky during the prayer?" His talk grew stern while delivering this speech and he said, "They should stop (looking towards the sky during the prayer); otherwise their eyesight would be taken away."