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.
nasai-kubra:544Ḥumayd b. Masʿadah > Bishr > Shuʿbah > al-Ḥakam > Ibrāhīm > ʿAbdullāh

[Machine] About the Prophet ﷺ concerning a man who greeted him while he was praying, he said, "Indeed, in prayer there is occupation."  

الكبرى للنسائي:٥٤٤أَخْبَرَنَا حُمَيْدُ بْنُ مَسْعَدَةَ قَالَ حَدَّثَنَا بِشْرٌ قَالَ حَدَّثَنَا شُعْبَةُ عَنِ الْحَكَمِ عَنْ إِبْرَاهِيمَ عَنْ عَبْدِ اللهِ

عَنِ النَّبِيِّ ﷺ فِي الرَّجُلِ يُسَلِّمُ عَلَيْهِ وَهُوَ يُصَلِّي قَالَ «إِنَّ فِي الصَّلَاةِ شُغْلًا»