The Messenger of Allah ﷺ forbade fasting on two days, the day of Fitr and the day of Adha.
أن رسول الله ﷺ نهي عن صيام يومين: يوم الفطر، ويوم ا الأضحى.
Malik narrated it in "Fasting" (36) from Muhammad bin Yahya bin Habban, from Araj, from Abu Hurairah, as mentioned.Muslim narrated it in "Fasting" (1138) through the route of Malik, with the same wording.Bukhari narrated it in "Fasting" (1993) through the route of Ata bin Mina, from Abu Hurairah, who said, "Two kinds of fasting and two kinds of transactions are forbidden, fasting on the day of Fitr and the day of Nahr, and mulamasah and munabadhah."Muslim narrated it through this same route in "Business Transactions" (1511:2), but did not mention the prohibition of fasting.