Answered by Shaykh Yusuf Weltch
Is it permissible to pray two rak‘a of ‘Isha sunna prayers behind an Imam who is praying Tarawih?
In the Name of Allah, the Most Merciful and Compassionate.
It is permissible to pray the sunna of ‘Isha prayer behind an Imam who is praying Tarawih.
Amongst the conditions for prayer behind an Imam to be valid is that the follower be in an equal or lesser state than the Imam in both the integrals of the prayer and its conditions. [Ibn ‘Abidin, Radd al-Muhtar]
Since the Imam is intending Tarawih (which is Sunna) and the follower is also intending a Sunna prayer, they are equal in state, and the prayer is valid.
An example of a prayer that is not valid is if the Imam is praying a sunna and the follower intends an obligatory prayer. [Ibid.]
Even though praying a voluntary prayer behind the Imam is valid, one should not make a habit of it. This is because in the Hanafi school, voluntary prayers, including Sunna prayers (not including Tarawih), are not prayed in the congregation.
Also, due to the strength of the Tarawih prayers in the Sunna, one does not combine the intentions of the Tarawih prayer and an emphasized Sunna prayer. For example, one does not combine the intention of the two units of emphasized sunna prayer after ‘Isha with the intention of two units of prayer of Tarawih.
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani
Shaykh Yusuf Weltch teaches Arabic, Islamic law, and spirituality. After accepting Islam in 2008, he completed four years at the Darul Uloom Seminary in New York, where he studied Arabic and the traditional sciences.
He then traveled to Tarim, Yemen, where he studied for three years in Dar al-Mustafa under some of the most outstanding scholars of our time, including Habib Umar Bin Hafiz, Habib Kadhim al-Saqqaf, and Shaykh Umar al-Khatib.
In Tarim, Shaykh Yusuf completed the memorization of the Quran and studied beliefs, legal methodology, hadith methodology, Quranic exegesis, Islamic history, and several texts on spirituality. He joined the SeekersGuidance faculty in the summer of 2019.