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Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
tabarani:11864 – Isḥāq b. Ibrāhīm al-Dabarī > ʿAbd al-Razzāq > Maʿmar > Ayyūb > ʿIkrimah

[Machine] On the authority of Ibn Abbas, I saw the Messenger of Allah prostrating in the letter 'ص' while it is not amongst the letters of Az'aim (sujud).  

الطبراني:١١٨٦٤ – حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ الدَّبَرِيُّ أَنَا عَبْدُ الرَّزَّاقِ أَنَا مَعْمَرٌ عَنْ أَيُّوبَ عَنْ عِكْرِمَةَ

عَنِ ابْنِ عَبَّاسٍ رَأَيْتُ رَسُولَ اللهِ ﷺ «يَسْجُدُ فِي ص وَلَيْسَتْ مِنَ الْعَزائِمِ»  

See similar narrations below:

Collected by Tirmidhī, Dārimī
tirmidhi:577 – Ibn Abū ʿUmar > Sufyān > Ayyūb > ʿIkrimah > Ibn ʿAbbās

"I saw the Messenger of Allah prostrating for (Surat) Sad." Ibn Abbas said: "It is not one of the resolute prostrations."  

الترمذي:٥٧٧ – حَدَّثَنَا ابْنُ أَبِي عُمَرَ حَدَّثَنَا سُفْيَانُ عَنْ أَيُّوبَ عَنْ عِكْرِمَةَ عَنِ ابْنِ عَبَّاسٍ قَالَ

رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَسْجُدُ فِي ص قَالَ ابْنُ عَبَّاسٍ وَلَيْسَتْ مِنْ عَزَائِمِ السُّجُودِ  

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ وَاخْتَلَفَ أَهْلُ الْعِلْمِ فِي ذَلِكَ فَرَأَى بَعْضُ أَهْلِ الْعِلْمِ مِنْ أَصْحَابِ النَّبِيِّ ﷺ وَغَيْرِهِمْ أَنْ يَسْجُدَ فِيهَا وَهُوَ قَوْلُ سُفْيَانَ الثَّوْرِيِّ وَابْنِ الْمُبَارَكِ وَالشَّافِعِيِّ وَأَحْمَدَ وَإِسْحَاقَ وَقَالَ بَعْضُهُمْ إِنَّهَا تَوْبَةُ نَبِيٍّ وَلَمْ يَرَوُا السُّجُودَ فِيهَا
darimi:1508 – ʿAmr b. Zurārah > Ismāʿīl > Ibn ʿUlayyah > Ayyūb > ʿIkrimah > Ibn ʿAbbās

A prostration when reciting Sad is not one of those which are divinely commanded, but I have seen Messenger of Allah ﷺ prostrate himself. (Using translation from Abū Dāʾūd 1409)   

الدارمي:١٥٠٨ – أَخْبَرَنَا عَمْرُو بْنُ زُرَارَةَ حَدَّثَنَا إِسْمَاعِيلُ هُوَ ابْنُ عُلَيَّةَ حَدَّثَنَا أَيُّوبُ عَنْ عِكْرِمَةَ عَنْ ابْنِ عَبَّاسٍ

أَنَّهُ قَالَ فِي السُّجُودِ فِي ص «لَيْسَتْ مِنْ عَزَائِمِ السُّجُودِ وَقَدْ رَأَيْتُ رَسُولَ اللَّهِ ﷺ سَجَدَ فِيهَا»