Maliks Muwatta Book 20, Hadith Number 137.
Section : Fasting on the Days of Mina.
Yahya related to me from Malik from Muhammad ibn Yahya ibn Habban from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, forbade fasting on two days – the day of the Id al-Fitr and the day of the Id al-Adha.