Prayer: Inadvertently Raising the Head from Sajdah Before the Imam
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1452
If a follower inadvertently raises his head and sees that the imam is in sajdah, then based on obligatory precaution, he must go back into sajdah. In the event that this happens in both sajdahs, then performing the two additional sajdahs, which constitute a rukn, does not invalidate the prayer.