Musnad Ahmad 163
Abu ‘Ubaid said:
I was present at Eid with ‘Umar, and he started with the prayer before the khutbah. He said: The Messenger of Allah ﷺ forbade fasting on 

these two days. The day of al-Fitr is the day when you break your fast, and on the day of al-Adha, 

eat the meat of your sacrifices.
حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، سَمِعَ أَبَا عُبَيْدٍ، قَالَ شَهِدْتُ الْعِيدَ مَعَ عُمَرَ فَبَدَأَ بِالصَّلَاةِ قَبْلَ الْخُطْبَةِ وَقَالَ إِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ نَهَى عَنْ صِيَامِ هَذَيْنِ الْيَوْمَيْنِ أَمَّا يَوْمُ الْفِطْرِ فَفِطْرُكُمْ مِنْ صَوْمِكُمْ وَأَمَّا يَوْمُ الْأَضْحَى فَكُلُوا مِنْ لَحْمِ نُسُكِكُمْ‏.‏