What is the evidence for 20 raka'ts Taraaweeh?

Answer

After the Ummah has performed 20 raka'ts Taraaweeh for 14 centuries, you now query the validity of this ibaadat as if the entire Ummah including all the Sahaabah and the illustrious Aimmah Mujtahideen and Fuqaha of all Four Math-habs were dumb and stupid like these Salafi morons who propagate 8 raka'ts. The Shariah is fourteen centuries old. There is no scope for change, interpolation and mutilation in Allah's Law. The evidence is the unbroken practice of the Ummah which is confirmed by the Four Math-habs of the Ahlus Sunnah Wal Jama'ah. Don't be duped by the juhala Salafis.