Prayer: Coughing, Groaning, or Sighing During Prayers
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1224
It is not obligatory for one to perform sajdatā al‑sahw for the sound he makes when coughing; however, if one inadvertently groans, sighs, or says ‘oh’, then based on obligatory precaution, he must perform sajdatā al‑sahw.