Some people say that fasting is forbidden on the day of Eid because satan used to fast on the day of Eid. Is this true according to Islam?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

As far as we know, it is not mentioned in any hadeeh that Satan fasts on the day of 'Eed. But it is confirmed that the Prophet forbade us from fasting on the day of 'Eed Al-Fitr and 'Eed Al-Adhha.

Shaykh ibn ‘Uthaymeen said:

“The wisdom in it is that the day of 'Eed Al-Fitr is the day of breaking the fast from Ramadan, and Ramadan cannot be specified [singled out] except by breaking the fast [not fasting] on the day of 'Eed. As regards 'Eed Al-Adhha, it is because it is the day of sacrifice, and if people were to fast on this day, they would have acted differently from what Allaah loves and ordered us to do in His saying {So eat of them and feed the miserable and poor.} [Quran 22:28]; how could a fasting person eat from them?”

Allaah knows best.