Musnad Abu Ya'la al-Mawsili 140:26

Abu Khaythama narrated to us, Rawh narrated to us, al-Rabi’ ibn Sabih and Masruq Abu ‘Abd Allah al-Sami narrated to us, they said: Yazid al-Raqashi narrated to us, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) forbade fasting the three days of al-Tashriq after the Day of Sacrifice.