Prayer: Saying Other Parts of the Prayer Before the Imam
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1449
Apart from takbīrat al‑iḥrām, there is no problem if a follower says other parts of the prayer before the imam. However, if he can hear those other parts or knows when the imam will say them, the recommended precaution is that he should not say them before the imam.