Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
tirmidhi:589Abū Ḥātim Muslim b. Ḥātim al-Baṣrī > Muḥammad b. ʿAbdullāh al-Anṣārī from his father > ʿAlī b. Zayd > Saʿīd b. al-Musayyab > Anas b. Mālik

"The Messenger of Allah said to me: 'O my son! Beware of looking around during the Salat, for indeed looking around during Salat is destruction. If you must do so, then in the voluntary (prayers), not in the obligatory (prayers).'" (Da'if)  

Abū ʿĪsá said that this Ḥadīth is Ḥasan-Ṣaḥīḥ.
الترمذي:٥٨٩حَدَّثَنَا أَبُو حَاتِمٍ مُسْلِمُ بْنُ حَاتِمٍ الْبَصْرِيُّ حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ الأَنْصَارِيُّ عَنْ أَبِيهِ عَنْ عَلِيِّ بْنِ زَيْدٍ عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ قَالَ قَالَ أَنَسُ بْنُ مَالِكٍ قَالَ

لِي رَسُولُ اللَّهِ ﷺ يَا بُنَىَّ إِيَّاكَ وَالاِلْتِفَاتَ فِي الصَّلاَةِ فَإِنَّ الاِلْتِفَاتَ فِي الصَّلاَةِ هَلَكَةٌ فَإِنْ كَانَ لاَ بُدَّ فَفِي التَّطَوُّعِ لاَ فِي الْفَرِيضَةِ  

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ