Is Salat al-Tasabih prescribed [in Islam], and what is the authenticity of its hadith? Is it permissible for mosques to perform it congregationally on the 29th night of Ramadan after Tarawih?

Scholars differed concerning the ruling on the Tasabih Prayer (Salat al-Tasabih) due to their disagreement on the authenticity of its hadith. The more preponderant opinion is that it is legislated (mashru'ah), as the hadith is strengthened by its numerous chains of transmission. It is permissible to pray it in congregation sometimes, but singling out the the 29th night for praying it in congregation is not established and is considered an additive innovation (bid'ah idafiyah). This is because adhering to a specific act of worship at a specific time that has not been ورد by the Sharia is an innovation.