Qiyām al-Layl in Ramadan was called Tarāwīh because the Companions and those who came after them used to prolong the standing, bowing, and prostration. When they finished four Rak‘ahs, they would take a rest (rest in Arabic: Rāhah) for a little while before praying another four, after which they would take another rest. They would pray the four with two Taslīms (i.e 2 Rak‘ahs then 2 Rak‘ahs). It is for this reason that this prayer came to be known as Tarāwīh, derived from the Arabic word Rāhah, and Allah knows best.
1187/1 - Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “He who offers Qiyām (voluntary night prayer) during the month of Ramadan out of Īmān (faith) and Ihtisāb (expecting the reward from Allah) will have his past sins forgiven.” [Narrated by Al-Bukhāri and Muslim]
1188/2 - He also reported: The Messenger of Allah (may Allah’s peace and blessings be upon him) would encourage the performance of Qiyām in Ramadan without giving an emphatic command about it. He would say: “He who offers Qiyām in Ramadan, faithfully and expecting its reward from Allah, will have his past sins forgiven.” [Narrated by Muslim]
An emphatic command: a confirmed command as that given with regard to obligatory acts of worship.
1) There is a great reward for those who perform Qiyām in Ramadan out of faith in Allah and in pursuit of reward from Him.
2) Qiyām in Ramadan is a confirmed Sunnah, which was done by the Prophet (may Allah’s peace and blessings be upon him) and the Companions after him. Blissful are those whom Allah guides to seizing the blessed opportunities during the nights of Ramadan.