Hudhaifah narrated that : he performed Salat with the Prophet, and that while he was bowing he would say: (Subhana Rabbiyal Azim); "Glorious is my Lord the Magnificent" and while prostrating: (Subhana Rabbiyal A'la) 'Glorious is my Lord the Most High.' And he would not recite an Ayah mentioning mercy, except that he would stop and ask (for mercy), and he would not recite an Ayah mentioning punishment, except that he would stop and seek refuge (with Allah from it).
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مَحْمُودُ بْنُ غَيْلاَنَ، حَدَّثَنَا أَبُو دَاوُدَ، قَالَ أَنْبَأَنَا شُعْبَةُ، عَنِ الأَعْمَشِ، قَالَ سَمِعْتُ سَعْدَ بْنَ عُبَيْدَةَ، يُحَدِّثُ عَنِ الْمُسْتَوْرِدِ، عَنْ صِلَةَ بْنِ زُفَرَ، عَنْ حُذَيْفَةَ، أَنَّهُ صَلَّى مَعَ النَّبِيِّ صلى الله عليه وسلم فَكَانَ يَقُولُ فِي رُكُوعِهِ " سُبْحَانَ رَبِّيَ الْعَظِيمِ " . وَفِي سُجُودِهِ " سُبْحَانَ رَبِّيَ الأَعْلَى " . وَمَا أَتَى عَلَى آيَةِ رَحْمَةٍ إِلاَّ وَقَفَ وَسَأَلَ وَمَا أَتَى عَلَى آيَةِ عَذَابٍ إِلاَّ وَقَفَ وَتَعَوَّذَ . قَالَ أَبُو عِيسَى وَهَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
sunnah.com