رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 1755
The Book of the Prohibited actions
Undesirability of Glancing in one Direction of the other during Prayer
عَنْ عَائِشَةَ رَضِيَ اللَّه عَنْهَا قَالَتْ: سَأَلْتُ رَسُولَ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ عَنْ الاِلْتِفَاتِ فِي الصَّلاَةِ فَقَالَ: هُوَ اخْتِلاَسٌ يَخْتَلِسُهُ الشَّيْطَانُ مِنْ صَلاَةِ الْعَبْدِ ((رَوَاهُ الْبُخَارِيّ)).
'Aishah (May Allah be pleased with her) said: I asked the Messenger of Allah (ﷺ) about random looks in Salat (prayer), and he replied, "It is something which Satan snatches from the slave's Salat." [Al-Bukhari].
Riyad as-Salihin, 1755