Question 017: How do I explain to my Muslim brothers that responding loudly after the Sheikh, during prayers is not part of Islam?
Answer 017: As for the Islamic laws, such as prayer, khums, zakat and etc., can only be determined by the divine legislator (share’: i.e. the acts of worship in which the contents (of prayer and etc.) are determined by the Holy Quran and traditions from the Holy Prophet (pbuh) and his household) which is called Ahkam Tauqifi, one who even has deep knowledge about Islam is unable to add anything other than what has been ordered by the divine legislator.

In prayer, one must not recite anything other than ‘ḏikr’; otherwise the prayer would become void. Just as the Shia have obtained all the rest of their teachings through the instructions and commandments of the Prophet and his household (pbuth), in this matter too they act in accordance to their instructions.

Based upon narrations, the Ahlul Bayt (pbuth) have told us that ‘saying ‘Ameen’ after reciting sūrah ‘al-Hamd’ is not part of the prayer, hence it is not permissible to say it’. It is narrated from Imam Sadiq (pbuh): ‘Whenever you are praying in congregation, and the leader of the congregation finishes reciting ‘Al-Hamd’, do not say ‘Ameen’, say instead ‘Alḥamdulillāh rabbi al-ʿālamīn’. [1]

The maraji’ have given the following fatwa based on the mentioned narration: ‘Of the acts which invalidate the prayer; is saying ‘Ameen’ after reciting ‘al-Hamd’, although if someone says it mistakenly or out of ‘taqīyah’ (dissimulation), the prayer is not void’. [2]

Finally, it is necessary to mention that according to Shīʿah Islamic law, it is not actually compulsory to say ‘Alḥamdulillāh rabbi al-ʿālamīn’ after ‘al-Hamd’; it is just mustahabb (recommended) . However, most Sunni schools of thought consider it an obligatory part of prayer, hence the onus is upon them to verify their claim through the Qur’ān and Prophetic Traditions.

Note: The traditions concerning the saying of Āmīn in prayer are of two types:

1) Traditions in which the chain of narrators includes Abu-Hurayrahh; e.g. “It is narrated from the Prophet (saws) that he said, ‘When the Congregation leader recites ‘walāḍ ḍāllīn’, you should say ‘Ameen’ because the angels [also] say ‘Āmīn’. Therefore every person who says Āmīn alongside with the angels will have all of his past sins forgiven.’”[3]

This group of traditions cannot be trusted due to the fact that the chain of narrators includes Abu Hurayrahh.[4]
Alī (as) says the following about Abu Hurayrah, “The most dishonest person in relation [to attributing lies] to the Prophet (saw) is Abu Hurayrah”[5] (i.e. he fabricated many traditions and attributed them to the Prophet (saw)).

2) Traditions in which the following people are included in the chain of narrators (of which none meet the criterion for being acceptable in terms of ‘hadīth’ narration): Ḥamīd ibn ‘Abd al-Raḥmān ibn Abī Laylī, Ibn ‘adī, ‘Abd al-Jabbar bin wa’il, Suhayl ibn Abī Suhayl, ‘ala’ ibn ‘Abd al-Raḥmān, and Talha ibn ‘Umar. Ḥamīd ibn ‘Abd al-Raḥmān ibn Abī Lalī possessed a weak memory and is considered ‘weak’ (in terms of narrating Hadīth), Ibn ‘adī is an unknown figure (majhul), ‘Abd al-Jabbār bin Waa’il cannot narrate from his father since his father died six months before he was born (in this respect the tradition is weak). Regarding Suhayl ibn Abī Suhayl and ‘Ala’ ibn ‘Abd al-Raḥmān, Abu Haatam says, “Their narrations are recorded (written down), however they bare no authority and Talha ibn ‘Umar is not usable (for narrating hadith), his traditions are extremely weak.”[6]

With the existence of such weak and unreliable narrators in the chain of narrations, these narrations have no credibility and cannot be trusted.

Some [scholars] have tried to justify saying Āmīn in prayer with the following explanation: “[We] say Āmīn because the phrase ‘Ihdinā ṣ-ṣirāṭ al-mustaqīm’ is a du‘a (supplication).”

In reply to this, it must be stated that this phrase only becomes a supplication if it is recited with the intention of supplicating, however those reciting it intend for it to be a part of the prayers and the Quran recited therein, not as a supplication.
Furthermore, if it were permissible to recite every supplicatory phrase for example ‘rabbanā aghfir lanā wa qinā ‘adhāba al-nār’ with the intention of supplicating, then it should also be permissible to recite Āmīn after every supplication, yet no one [of the scholars] holds this view.[7]

For further information in this regards, please refer to the following answer:

Index: Number of things which invalidate the prayer, answer 547.

[1] Tusi, Muhammad bin al-Hasan, al-Tahdhib, vol. 2, pg. 74.

[2] Tawdih al-Masa’il (annotated by Imam Khomeini), vol. 1, pg. 617. This ruling is agreed upon by all the respected jurists.

[3] . Baydawi, Naasir al-Din Abu al-Khayr Abdullah ibn Umar, Anwaar al-Tanzil wa Asraar al-Ta’wil, vol. 1, p. 32, Ihyaa’ al-Turaath al-Arabi Press, Beirut, 1418 AH.

[4] . Abu Hurayrah Abd al-Rahmaan ibn Sakhr al-Azudi (22 BH-59 AH): eight hundred Sahaabis and Taabi’is have narrated from him. During his rule, Umar appointed him as governor of Bahrain, but due to his weakness in character and leniency, he was dismissed from this responsibility. He spent most of his life in Medinah. Taqiyuddin Sabki has a booklet entitled “Fataawaa Abi Hurayrah”, and Abd al-Husayn Sharafuddin has a book entitled “Abu Hurayrah” on him. (Al-A’laam 4/80, 81). Hujjati, Asbaab al-Nuzul, p. 216.

[5] . See: Ibn Abi al-Hadid Mu’tazili, ‘Izz al-Din Abu Hamed, Sharh Nahjul-Balaghah, vol. 4, p. 68, Library of Ayatullah Mar’ashi Najafi, 1956, first edition.

[6] . See: Sultani, Abd al-Amir, Hukm al-Ta’min fi al-Salah, Ahlul Bayt World Assembly, second edition.

[7] . See: Sabzawari, Ali Mu’min Qummi, Jaami’ al-Khilaaf wa al-Wifaaq bayn al-Imaamiyyah wa bayn A’immat al-Hijaaz wa al-Iraaq, Zamineh Saazane Zuhure Imam Zamaan Press, 1421 AH, first edition, Qum.