Sahih al-Bukhari 751
Book 10: Call to Prayers (Adhaan) · Narrated by `Aisha
Arabic
حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا أَبُو الأَحْوَصِ، قَالَ حَدَّثَنَا أَشْعَثُ بْنُ سُلَيْمٍ، عَنْ أَبِيهِ، عَنْ مَسْرُوقٍ، عَنْ عَائِشَةَ، قَالَتْ سَأَلْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ الاِلْتِفَاتِ فِي الصَّلاَةِ فَقَالَ " هُوَ اخْتِلاَسٌ يَخْتَلِسُهُ الشَّيْطَانُ مِنْ صَلاَةِ الْعَبْدِ ".
English translation
Narrated `Aisha:I asked Allah's Messenger (ﷺ) about looking hither and thither in prayer. He replied, "It is a way of stealing by which Satan takes away (a portion) from the prayer of a person
Reference: Sahih al-Bukhari 751, Book of Call to Prayers (Adhaan). English translation by Dr. Muhammad Muhsin Khan.