Prayer: Forgetting a Non-Rukn and Performing the Next Non-Rukn
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1098
If a person forgets something that is not a rukn and performs the act that comes after it that is not a rukn either – for example, he forgets Sūrat al-Ḥamd and recites the other surah – he must perform the act he forgot and then perform the act he mistakenly performed before it.