The Prayer of the Two Eids
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 79
وَ سُئِلَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: عَنْ صَلاَةِ اَلْأَضْحَى وَ اَلْفِطْرِ فَقَالَ «صَلِّهِمَا رَكْعَتَيْنِ فِي جَمَاعَةٍ أَوْ فِي غَيْرِ جَمَاعَةٍ وَ كَبِّرْ سَبْعاً وَ خَمْساً.
Imam Jafar ibn Muhammad Al-Sadiq عليه السلام was asked about the prayers of Eid al-Adha and Eid al-Fitr, and He said: "Pray them as two units (rak'ahs), either in congregation or individually, and say seven takbirs (Allahu Akbar) in the first rak'ah and five in the second”.
- Ṣaḥīḥ al-Faqīh