Prayer: Omitting or Adding a Rukuʿ
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1494
Every rukūʿ of ṣalāt al‑āyāt is a rukn; therefore, if a rukūʿ is intentionally omitted or added, the prayer is invalid. The same applies if a rukūʿ is mistakenly omitted or, based on obligatory precaution, if it is mistakenly added.