What is Tarāweeḥ?
Tarāweeḥ is a special night prayer that is performed during the month of Ramaḍān. It serves to maximise good deeds that can be done during this time, along with many other benefits, such as allowing people to listen to the Qur'an, bringing the Muslims together, and attaching people to the mosque.
Is Tarāweeḥ obligatory?
Tarāweeḥ itself is optional, because the Prophet (may the peace and blessings of Allah be upon him) prayed it for a time and then stopped. He led his companions in tarāweeḥ prayer for several nights, then on the third or fourth night he did not come out to them. When morning came he said:
"Nothing prevented me from coming out to you except the fact that I feared that it would be made obligatory for you." [al-Bukhārī: 1129; Muslim: 761]
The Reward of Tarāweeḥ
The Prophet (may the peace and blessings of Allah be upon him) said:
"Whosoever performs (optional Tarāweeḥ) prayers at night during the month of Ramadan, with Faith and in the hope of receiving Allah's reward, will have his past sins forgiven." [Muslim: 759]
Abū Dharr (may Allah be pleased with him) narrated that the Prophet (may the peace and blessings of Allah be upon him) said:
"...Whoever stands with the imām until he finishes, it is equivalent to spending the whole night in prayer..." [at-Tirmidhi: 806]
How should the Tarāweeḥ be prayed?
The tarāweeḥ should be prayed in sets of two rak'ah. This is because of the following narration of Ibn 'Umar (may Allah be pleased with him) that the Messenger of Allah (may the peace and blessings of Allah be upon him) said:
"Prayer at night is two by two, and witr is one rak'ah." [an-Nasā'ī: 1693]
How many rak'ah should be prayed?
Since the prayer is optional, you may pray any number of units that you wish, as long as the total number, including the witr prayer is odd.
It is known through various narrations that both inside and outside of Ramaḍān, the Prophet (may the peace and blessings of Allah be upon him) would pray eleven rak'ah for the night prayer (eight for the tarāweeḥ, plus the witr).
Abū Salamah ibn 'Abdurraḥmaan (may Allah have mercy on him) narrated that he asked 'Aa'ishah (may Allah be pleased with her) about the prayer of the Messenger of Allah (may the peace and blessings of Allah be upon him) in Ramaḍān. She replied:
"Allah's Messenger (may the peace and blessings of Allah be upon him) never exceeded eleven rak'ah in Ramaḍān or in other months..." [al-Bukhārī: 1147]
Having said that, there is no problem with praying a number larger than eight, as is reported from some of the well known scholars of the early generations. The evidence for this is the general statement of the Prophet (may the peace and blessings of Allah be upon him):
"Prayer at night is two by two, and witr is one rak'ah." [an-Nasā'ī: 1693]
It is important to pray from start to finish with the imām, no matter what the number, as this holds the most reward. This is mentioned in the following narration of Abū Dharr (may Allah be pleased with him) that the Prophet (may the peace and blessings of Allah be upon him) said:
"...Whoever stands with the imām until he finishes, it is equivalent to spending the whole night in prayer..." [at-Tirmidhi: 806]