Reciter seeking refuge with Allah if he recites a verse that mentions punishment
باب تَعَوُّذِ الْقَارِئِ إِذَا مَرَّ بِآيَةِ عَذَابٍ
Sunan an-Nasa'i, Book of The Commencement of the Prayer(view book)
Sunan an-Nasa'i 1008
It was narrated from Hudhaifah that:
He prayed beside the Prophet ﷺ one night. He recited, and when he came to a verse that mentioned punishment, he would pause and seek refuge with Allah; if he came to a verse that mentioned mercy, he would pause for mercy. In his bowing he would say: 'Subhana Rabbil-Azim (Glory be to my Lord Almighty)' and in his prostration he would say: 'Subhan Rabbil-A'la (Glory be to my Lord the Most High).'"
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا يَحْيَى، وَعَبْدُ الرَّحْمَنِ، وَابْنُ أَبِي عَدِيٍّ، عَنْ شُعْبَةَ، عَنْ سُلَيْمَانَ، عَنْ سَعْدِ بْنِ عُبَيْدَةَ، عَنِ الْمُسْتَوْرِدِ بْنِ الأَحْنَفِ، عَنْ صِلَةَ بْنِ زُفَرَ، عَنْ حُذَيْفَةَ، أَنَّهُ صَلَّى إِلَى جَنْبِ النَّبِيِّ ﷺ لَيْلَةً فَقَرَأَ فَكَانَ إِذَا مَرَّ بِآيَةِ عَذَابٍ وَقَفَ وَتَعَوَّذَ وَإِذَا مَرَّ بِآيَةِ رَحْمَةٍ وَقَفَ فَدَعَا وَكَانَ يَقُولُ فِي رُكُوعِهِ " سُبْحَانَ رَبِّيَ الْعَظِيمِ " . وَفِي سُجُودِهِ " سُبْحَانَ رَبِّيَ الأَعْلَى " .