Yazid bin al-Had narrates from Abu Murrah (may Allah have mercy on him), the freed slave of Umm Hani (may Allah be pleased with her), that he went with Abdullah bin Amr (may Allah be pleased with them both) to Amr bin al-As (may Allah be pleased with him). He brought food near to them and said: "Eat." He said: "I am fasting." So Amr (may Allah be pleased with him) said: "Eat, for these are the days on which the Messenger of Allah (peace and blessings be upon him) used to command us to break the fast and used to forbid us from fasting on them." Malik (may Allah have mercy on him) said: They were the days of Tashriq.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8461