Rationally, prayer must consist only of established acts and phrases taught by the Prophet ﷺ. Any additional utterance within prayer requires explicit proof that the Prophet included it as part of ṣalāh.

From the Qur’anic perspective, Surah al-Fātiḥah itself is a complete supplication ending with:

> “Guide us to the straight path.” (Qur’an 1:6)

There is no Qur’anic instruction to add any word after it within the prayer.

From Sunni hadith literature:

Ṣaḥīḥ Muslim narrates that the Prophet ﷺ said “Āmīn” after finishing al-Fātiḥah, but the reports differ on whether it was inside the formal prayer text or a congregational response.

Imam Mālik held that saying Āmīn aloud is not part of the prayer, and in the Maliki school it is often omitted entirely. Therefore, the Shiʿi omission of “Āmīn” is supported by recognized Sunni juristic opinions and is not a deviation.