How is the Salat al-Tasbih performed?

There are narrations in some hadith collections regarding the description of Salat al-Tasbih. The Messenger of Allah (peace and blessings be upon him) recommended and taught this prayer to his uncle Abbas (may Allah be pleased with him), saying, "O uncle, shall I not teach you something that has ten benefits? If you do this, Allah will forgive your ten types of sins: the first and last, old and new, those you committed knowingly and unknowingly, the small and the great, and those done secretly and openly." When Abbas replied that he could not perform it every day, the Prophet stated that performing this prayer once a week, once a month, once a year, or even once in a lifetime would suffice. (Abu Dawud, Tatavvu‘, 302 [1297]; Ibn Majah, Iqamat al-Salawat, 190 [1387])

Salat al-Tasbih consists of four rak‘ahs and is performed as follows: One begins with the intention of "performing Salat al-Tasbih for the sake of Allah." After reciting Subhanaka, the phrase "Subhanallahi wal-hamdu lillahi wa la ilaha illallahu wallahu akbar" is recited 15 times. Then, after reciting the ta‘awwudh and basmalah, Surah al-Fatiha and another surah are recited, followed by reciting the same tasbih 10 more times. This tasbih is then recited 10 times in ruku‘, 10 times after rising from ruku‘, 10 times in the first prostration, 10 times after rising from prostration, and 10 times in the second prostration. Thus, 75 tasbihs are recited in each rak‘ah. Upon standing for the second rak‘ah, the tasbih is recited 15 times before the recitation, then after the basmalah, Surah al-Fatiha and another surah are recited, followed by 10 tasbihs. The remaining rak‘ahs are performed in the same manner, completing four rak‘ahs and a total of 300 tasbihs.

Salat al-Tasbih is not performed during the disliked times for prayer. (Ibn Abidin, Radd al-Muhtar, 2/27) If an action requiring the prostration of forgetfulness (sujud al-sahw) occurs during Salat al-Tasbih, the prostration is performed as usual, but the tasbihs specific to Salat al-Tasbih are not recited in those prostrations. (Tahtawi, Hashiyah, 361)

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu