Jami` at-Tirmidhi 2894
جامع الترمذي#2894Sahihحَدَّثَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ أَخْبَرَنَا يَزِيدُ بْنُ هَارُونَ، قَالَ أَخْبَرَنَا يَمَانُ بْنُ الْمُغِيرَةِ الْعَنَزِيُّ، حَدَّثَنَا عَطَاءٌ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا زُلْزِلَتِ تَعْدِلُ نِصْفَ الْقُرْآنِ وَقُلْ هُوَ اللَّهُ أَحَدٌ تَعْدِلُ ثُلُثَ الْقُرْآنِ وَ قُلْْ يَا أَيُّهَا الْكَافِرُونَ تَعْدِلُ رُبُعَ الْقُرْآنِ " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ غَرِيبٌ لاَ نَعْرِفُهُ إِلاَّ مِنْ حَدِيثِ يَمَانِ بْنِ الْمُغِيرَةِ .
Narrated Ibn 'Abbas:that the Messenger of Allah (ﷺ) said: "Idha Zulzilat is equal to half of the Qur'an, Qul Huwa Allahu Ahad is equal to a third of the Qur'an, and Yul Ya Ayyuhal-Kafirun is equal to a fourth of the Qur'an
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 45:20