Sahih al-Bukhari 3291
Book 59: Beginning of Creation · Narrated by `Aisha
Arabic
حَدَّثَنَا الْحَسَنُ بْنُ الرَّبِيعِ، حَدَّثَنَا أَبُو الأَحْوَصِ، عَنْ أَشْعَثَ، عَنْ أَبِيهِ، عَنْ مَسْرُوقٍ، قَالَ قَالَتْ عَائِشَةُ ـ رضى الله عنها ـ سَأَلْتُ النَّبِيَّ صلى الله عليه وسلم عَنِ الْتِفَاتِ الرَّجُلِ فِي الصَّلاَةِ. فَقَالَ " هُوَ اخْتِلاَسٌ يَخْتَلِسُ الشَّيْطَانُ مِنْ صَلاَةِ أَحَدِكُمْ ".
English translation
Narrated `Aisha:I asked the Prophet (ﷺ) about one's looking here and there during the prayer. He replied, "It is what Satan steals from the prayer of any one of you
Reference: Sahih al-Bukhari 3291, Book of Beginning of Creation. English translation by Dr. Muhammad Muhsin Khan.