This hadith has been narrated on the authority of Zuhri with the same chain of transmitters that be heard Allah's Apostle ﷺ 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.

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 .