Answered by Shaykh Faraz Rabbani
Question: What is the ruling of the Tarawih prayer? I heard that Hazrat Umar was the first person to start this practice and he himself called it a good innovation
Answer: In the Name of Allah, Most Merciful
Sayyiduna Umar was using the linguistic meaning of bid`a, namely, something not done before, when he referred to tarawih as “an excellent bid`a”. Of such new matters, those in line with the Prophetic guidance are accepted; those against it are not. As Sayyiduna Umar’s ijtihad was in line with the guidance of the Messenger of Allah (Allah bless him and give him peace), it was not only acceptable, but most praiseworthy and was thus accepted by the consensus of the Companions of the Prophet (Allah bless him and give him peace), and subsequent generations.
The Ruling of the Tarawih Prayer
For men, it is recommended (mustahabb) to pray tarawih in congregation. [Haskafi, Durr al-Mukhtar]
As such, praying it alone is not sinful, unlike making it a habit to leave a confirmed sunna (such as the 20 rakats of tarawih), which is sinful.