Is it compliant with the Sunnah to say Aameen out loud (without startling the people around) once the imam completes Surat-ul-Faatihah in the obligatory prayer according to all the Schools of Thought? (Sadly, the small differences in the opinions regarding the Sunnah rituals of the prayers, specifically the obligatory ones, are becoming a cause of problems amongst the Muslims.) How strong is the opinion in favour or against this in the authentic hadiths? Furthermore, can the imam issue any opinion or fatwa (if an authentic hadith supports silent Aameen quietly) to the effect that those who do not agree with the silent saying of Aameen should go to other mosques, where it is accepted. My question regarding this is: is it permissible in Sharia for the imam to tell people to go elsewhere, to other mosques, just because of the issue of this Sunnah Ritual in the obligatory prayer? Thank you in advance for your considered opinions.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

That the person led in prayer says Aameen aloud is a recommended Sunnah (Mustahab) according to some scholars of Fiqh, not in all the Schools of Thought.

The imaam does not have the right to tell the congregation to choose between saying Aameen silently or praying in another mosque. Indeed, the mosques are the Houses of Allah, and any Muslim who wishes to pray in the mosque may do so, and he is not expelled from it or denied access due to an issue of difference of opinion which the hearts should accommodate.

We have already issued fatwa 326020 clarifying the statements of the scholars of Fiqh about saying Aameen aloud, and we favored the view that this is permissible for both the imaam (the person leading the prayer) and the congregation (people led in the prayer).

It should be noted that bringing the hearts together and avoiding dissension and discord is one of the objectives of the Shariah. So this objective should not be wasted due to an issue that scholars differed about and is at best recommended, not an obligation (Fardh).

So if doing what is recommended leads to dissension and discord among the worshipers, then it is more appropriate to abandon it because of the benefit of comforting the hearts and uniting the Muslims along with trying to teach them the Sunnah and urging them to practice it.

Shaykh-ul-Islam Ibn Taymiyyah, may Allah have mercy on him, said:

"A Muslim may abandon what is recommended if doing it brings about a disadvantage that overweighs its benefit, just as the Prophet abandoned building the Ka‘bah according to the foundations laid by Ibraaheem (Abraham), and he said to ‘Aa’ishah, 'Were it not that your people (i.e. Quraysh) are new Muslims (i.e. they have only recently left disbelief behind), I would have demolished the Ka‘bah and rebuilt it at the ground level and made two doors for it, one for the people's entrance and one for their exit.' [Al-Bukhaari and Muslim]

Therefore, the Prophet refrained from what he perceived as the better of two things because there was a preponderant disadvantage in doing so, which was repelling Quraysh given that they had only recently become Muslim, so the disadvantage overweighed the benefit [and this is why he did not rebuild it].

It is for this reason that Imaam Ahmad and others favored that the imaam should leave what is better if by doing so softening of the hearts takes place, such as if the imaam favors praying the Witr prayer two Rak’ahs (units of prayer) and then one Rak’ah while he leads a people who believe in praying the Witr as three Rak’ahs altogether with one Tashahhud. So if he could not do what is better, the preponderant interest is to comply with them; meaning: to pray the three Rak’ahs of the Witr with one Tashahhud, and this is more preponderant than the benefit of praying the Witr as two Rak'ahs and then one Rak'ah separately while the congregation dislikes praying behind him for doing so. Also, if he is of the view that reciting the Basmalah silently (in one’s heart) is better or that reciting it aloud is better and the congregation is of a different view than his, then it is permissible and good for him to do what is less preferable for him for the sake of complying with the congregation and softening their hearts, which is more important than the benefit of doing what he sees as more preferable."

For more benefit, please refer to fatwa 331852.

Allah knows best.