Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.147B.

Section : Eating on the two ‘ids.

One is to eat before going to the salah for ‘idul fitr, (the end of Ramadan) but not do so on the occasion of the ‘idul azha (commemorating Prophet Ibrahim’s  sacrifice). For ‘idul fitr, it is a sunnah to eat an odd number of dates before going to pray salatul ‘id while for ‘idul azha the eating should be delayed until one returns from the ‘id prayers and then he may eat of his sacrifice if he has sacrificed an animal.

Anas reports: “The Prophet would not go out on the festival of breaking the fast until he had eaten an odd number of dates.” This is related by Ahmad and al-Bukhari.

Buraidah reports: “The Prophet would not go out on the day of breaking the fast (‘idul fitr) until he had eaten and on the day of sacrifice (‘idul azha) he would not eat until he had returned [from salah].” This is related by at-Tirmizhi and Ibn Majah, and also by Ahmad who added: “And he would eat from his sacrifice.”

In al-Muwatta’ it is recorded from Sa’id ibn al-Musayyab that the people were ordered to eat before they go out on the day of breaking the fast.

Ibn-Qudamah said: “I do not know of any difference of opinion over the fact that one should hasten in eating [eat early] on the day of breaking of the fast.”