Hadith 916
Chapter 26: The Interpretation of the saying of Allah, The Mighty and Sublime: And Indeed, "We have - كتاب الافتتاح
أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ حَدَّثَنَا شَرِيكٌ، عَنْ أَبِي إِسْحَاقَ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، فِي قَوْلِهِ عَزَّ وَجَلَّ { سَبْعًا مِنَ الْمَثَانِي } قَالَ السَّبْعُ الطُّوَلُ .
It was narrated that Ibn Abbas said:
Concerning the words of Allah, the Mighty and Sublime: "Seven of Al-Mathani (seven repeatedly-recited): "The seven long ones."
Reference : Sunan an-Nasa'i 916
In-book reference : Book 11, Hadith 41