SHAFAQNA – The Grand Ayatollah Khamenei answered questions about reciting Tasbihatul Arba’ah.
Question: 1) What is the duty if there is a doubt in third and fourth Rok’at that Tasbihatul Arba’ah has been recited twice or three times? 2) What is the duty if we doubt a lot about this and it develops into an obsession?
The Grand Ayatollah Khamenei: 1) You can recite Tasbihat once more. 2) Must not pay attention to doubt and think that the third Tasbihat has been recited.
Source: PERSIAN SHAFAQNA