Abu ‘Essa Tirmidhi (Died 279 AH) narrated :
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ الْمَلِكِ بْنِ أَبِي الشَّوَارِبِ، حَدَّثَنَا يَحْيَى بْنُ عَمْرِو بْنِ مَالِكٍ النُّكْرِيُّ، عَنْ أَبِيهِ، عَنْ أَبِي الْجَوْزَاءِ، عَنِ ابْنِ عَبَّاسٍ، قَالَ: ضَرَبَ بَعْضُ أَصْحَابِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ خِبَاءَهُ عَلَى قَبْرٍ، وَهُوَ لَا يَحْسِبُ أَنَّهُ قَبْرٌ، فَإِذَا فِيهِ إِنْسَانٌ يَقْرَأُ سُورَةَ تَبَارَكَ الَّذِي بِيَدِهِ الْمُلْكُ حَتَّى خَتَمَهَا، فَأَتَى النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ، فَقَالَ: يَا رَسُولَ اللَّهِ، إِنِّي ضَرَبْتُ خِبَائِي عَلَى قَبْرٍ، وَأَنَا لَا أَحْسِبُ أَنَّهُ قَبْرٌ فَإِذَا فِيهِ إِنْسَانٌ يَقْرَأُ سُورَةَ تَبَارَكَ الْمُلْكُ حَتَّى خَتَمَهَا، فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: هِيَ الْمَانِعَةُ هِيَ الْمُنْجِيَةُ تُنْجِيهِ مِنْ عَذَابِ الْقَبْرِ ، قَالَ أَب
” Ibn ‘Abbas narrated: ” One of the Companions of the Prophet put up a tent upon a grave without knowing that it was a grave. There was a man in it who was reciting Sürah Al-Mulk untill he completed it. Then he went to the Prophet ; and said: ‘0 Messenger of Allah [Indeed] I erected my tent without realizing that it was upon a grave. There was a person in it who recited Sürah Al-Mulk until its completion.’ So the Prophet said: ‘It is a prevention, it is a salvation delivering from the punishment of the grave.”
Also in another translated version.
Now same narration is translated by Abu Khallyl (US) he translated a segment to like this :
” So when I realized there was a person in it I recited Sürat Al-Mulk until its completion .”
As this narration wasn’t in accordance with what modern salafis believe. So this translator made a vague attempt to mistranslate this segment in the narration.