Prayer: Doubting Whether a Sajdah or Tashahhud Was Forgotten
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1244
If a person does not know whether he has forgotten a sajdah or tashahhud in prayers, he must make up the sajdah and perform sajdatā al‑sahw. And the recommended precaution is that he should also make up the tashahhud.