During Eid al -Adha and three days later, Muslims are forbidden to fast.

Is it OK to fast on Eid?

Days when fasting is forbidden

Although fasting is considered a pious act in Islam, there are times when fasting is considered prohibited or discouraged according to the majority of the sunni scholars: Eid al-Adha and three days following it, because Muhammad said "You are not to fast these days.

Is it sunnah to fast before Eid prayer?

Eating before Eid ul Fitr prayer is count as a Sunnah. Eid ul Fitr is the religious festival of Muslims that also known as the fast-breaking festival; celebrate on First Shawwal, 10th month of the Islamic lunar calendar. ...