There is no mention of Taraweeh in the Quran. These were initiated at the time of Allah's Messenger or of Hazrat Umar's. This is a question in history. The Shias and the sunnis have disagreement over it. Everyone is aware of these discussions and controversies. On the question whether the number of rak'ahs in Taraweeh is eight or twenty, there is a disagreement within the sunnis itself. And no one is unaware of these debates.
Islam is the name of the life for preserving a human being, within the boundary walls of the Quran. For this purpose, it is necessary that all humans (Muslims) must know, as to what are the boundary walls of the Quran and along with it, they must also get themselves, up for self-control. The month of Ramadan is the specific instrument for inculcating and substantiating each of these two matters: (i) what are the boundary walls of the Quran; and (ii) getting him/herself up for self-control. In the modern terminology, call it Training classes or a Refresher Course. Fasting makes humans get themselves up for leading striven-life through self-control. And its fixing is in this month, wherein the beginning of revelation of the Quran was initiated.
So it brings this stark fact to the fore-front. Special arrangements during this Training Course should be made for gushing forth the entire Quran to the striven-people, the Mujahideen so that they may fully comprehend, as to what the connection of "the sword and the Quran" is with each other; and That is how these two, "the sword and the Quran", became the instrument for safeguarding each other.
It appears that the Islamic system of the First Era was made, in order to bring the Quran, to the mind of the people, all at the same time and this method is now being performed, only to attain the reward of a virtuous act (Sawaab). It is because the way the Quran is recited now, during the Taraweeh, is neither understood by the Quran-conner, who causes others to hear it, as to what he had recited, nor do the disciples in the congregation comprehend as to what they have listened.
And it is obvious, that the way, the words of the Quran are repeated and heard without being understood, therefore, cannot make the exposition of the Quran understandable. And neither can it be known which design of life it carves for us. When the system of caliphate based on the precept of Nabuvva is established, its job will be to oversee, as to where the revamping is essential in our traditional mores and cores of life. It will then be the time, whence-fore the correct concept of "Sin and Sawaab" would come to the fore-view of the masses.