أخطاء المصلين
Anas (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said to him: "O son, beware of looking around in prayer, as looking around in prayer is destruction! If you must do so, then let it be in the voluntary (prayer) not the obligatory one."
عن أنس -رضي الله عنه- قال: قال لي رسول الله -صلى الله عليه وسلم-: «يا بُنَيَّ، إِيَّاك والالتِفَات في الصلاة، فإن الالتِفَات في الصلاة هَلَكَة، فإن كان لا بُدَّ ففي التَّطَوُّعِ لا في الفَريضة».
شرح الحديث :
The Prophet (may Allah's peace and blessings be upon him) warned Anas (may Allah be pleased with him) against looking around during the prayer, and informed him that such an act leads to destruction, since it is obedience to the devil, who is the reason for perdition. Looking around in prayer renders it from being complete to being deficient, and one could even reach the extent of coming out of prayer with no reward at all. However, if one must look around and there is no way to avoid that, then let it be done in the voluntary prayer, since the matter with regard to the voluntary prayer is lighter than the obligatory prayer.