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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
muslim:1129c – Ibn Abū ʿUmar > Sufyān b. ʿUyaynah > al-Zuhrī Bihadhā al-Isnād

I am fasting today, so he who wishes to observe fast should do so; but he did not make mention of the rest of the hadith.  

مسلم:١١٢٩c – وَحَدَّثَنَا ابْنُ أَبِي عُمَرَ حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ عَنِ الزُّهْرِيِّ بِهَذَا الإِسْنَادِ

سَمِعَ النَّبِيَّ ﷺ يَقُولُ فِي مِثْلِ هَذَا الْيَوْمِ إِنِّي صَائِمٌ فَمَنْ شَاءَ أَنْ يَصُومَ فَلْيَصُمْ وَلَمْ يَذْكُرْ بَاقِيَ حَدِيثِ مَالِكٍ وَيُونُسَ