وَحَدَّثَنَا ابْنُ أَبِي عُمَرَ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، بِهَذَا الإِسْنَادِ سَمِعَ النَّبِيَّ صلى الله عليه وسلم يَقُولُ فِي مِثْلِ هَذَا الْيَوْمِ ‏"‏ إِنِّي صَائِمٌ فَمَنْ شَاءَ أَنْ يَصُومَ فَلْيَصُمْ "‏ ‏.‏ وَلَمْ يَذْكُرْ بَاقِيَ حَدِيثِ مَالِكٍ وَيُونُسَ ‏.‏

This hadith has been narrated on the authority of Zuhri with the same chain of transmitters that be heard Allah's Apostle (PBUH) as saying on a similar day: 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. Translation Not Available

Book Ref: Sahih Muslim Book 13 Hadith 2517
Web Ref:  Sahih Muslim Book 6 Hadith 1129 c