Imam Ghazali said in Ihya’ `Ulum al-Din: “Fasting is definitely desirable in certain meritorious days, some of them being found in every year, others in every month, and others in every week. Those that are found in every year after the days of Ramadan are:
And all the sacred months are preferred for fasting… and they are:
Dhu al-Qi`da, Dhu al-Hijja, Muharram, and Rajab.”
`Abd Allah ibn Mas`ud said: The Prophet ﷺ said: “There are no days in the year in which deeds are more meritorious than in the Ten Days [i.e. the first ten days of Dhu al-Hijja].” Someone asked: “Not even Jihad in the path of Allah?” He replied: “Not even Jihad in the path of Allah.” Haythami said: “Tabarani narrated it in al-Mu`jam al-kabir and the narrators in its chain of transmission are all those of sound (sahih) narrations.
The nights are included in the mention of the days. Allah swore an oath by them when He said: “By the Dawn! By Ten Nights!” (89:1-2) and the authors of Tafsir al-Jalalayn said: “They are the first ten nights of Dhul Hijja.”
The `Eid prayer is a Sunnah mu’akkada or confirmed Sunnah and is recommended to be prayed in congregation. It is wajib (obligatory) in the Hanafi madhhab and therefore required of every person who is required to perform Jum`a, i.e. healthy male residents of the region in which it is performed.
It is a Sunnah mu’akkada and, in the Hanafi madhhab, a wajib, for every adult Muslim man and woman to sacrifice at least one shat — a sheep or a goat — for `Eid al-Adha. This may be done any time after the prayer on the first day of `Eid until sunset on the last of the two days following the first day. One may have someone else perform the sacrifice on his behalf, whether in his presence or in absentia.
It is recommended not to eat anything on the day of `Eid al-Adha until one perform the Prayer.
It is recommended to perform ghusl (major ablution) before the prayer, any time after Fajr even if one does not attend the prayer.
It is recommended for men to dress their best and wear perfume. It is Sunnah to come to the mosque early and on foot, and to return home by a different route. It is preferable for a `Eid Congregation to pray outdoors.