Shaikh Ibn ul-‘Uthaymeen رحمه الله تعالى
“The head is not to be raised during prayer,not even during du’a qunoot,not when raising up from rukoo’,not when sitting between the prostrations…never. Since raising the eyesight up during the prayer is prohibited.
The Prophet صلى الله عليه و سلم warned against that severely, ”They must stop that, or their eyesight may be snatched away”.(Bukhary 750)
In another narration equally severely, ”The people must stop raising their eyesight up to the sky in Prayer, otherwise it may not return to them”.(Muslim 428).
These narrations indicate it is actually prohibited to raise the eyesight and look around during prayer (not as some think that it’s no considerable issue), and in fact it is a major sin.
Some scholars even have an opinion that the one who raises his eyesight during the prayer nullifies his prayer and must start again.
People who look around and raise their eyesight must stop, lest they may be blinded due to this act, such is the severity of the warning”.
[صفة الصلاة 74]