Assalaamu alaykum. Please answer me directly without refering to another fatwa. If, after entering the masjid, I found that the imam makes clear major mistakes in Surat Al-Faatihah, as he is weak in recitation, while I know the correct recitation, should I join him or pray alone? Or should I join him first and then repeat the prayer? Praying alone while the prayer in congregation is being held nearby does not look good.

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.

First of all, you should know that the recitation of the imaams and their prayers are valid in principle, and there is no need to have doubts in this regard.

However, if you are certain that the imaam makes mistakes in Al-Faatihah that change the meaning, and that if he is taught he does not learn, then there is a difference of opinion about praying behind him. If you avoid praying behind him, then this is good; and if you follow the view of the scholars who held that it is permissible to pray behind him, then there is no harm on you, Allah willing.

The same applies if he changes one letter with another letter that is close in pronunciation, such as (ظاء- ضاد) and (طاء - تاء) and so on. Many scholars were lenient with regards to such mistakes because they are widespread and it is difficult to avoid them.

So if the imaam is one who, if he is taught, learns, and his mistakes are other than the ones we mentioned, then do not pray behind him because the prayer behind him is not valid in this case.

In this case, you do whatever you deem appropriate and beneficial in a way that does not cause fitnah (tribulation/dissension) among the worshipers and provided that you advise this imaam and try to teach him the right way of recitation.

Allah knows best.