Question 23: A man entered the Masjid (mosque) after the first congregational Salaah (Prayer) was over to find another congregational Salaah led by an illiterate Imaam (the one who leads congregational Prayer). Such a person who is well-aware of the proper recitation of Qur’aan thought it was not right to join this congregational Salaah. Should he have joined them? If he had joined them to attain the reward of offering congregational Salaah, would his Salaah have been valid?
Answer: If the unlettered Imaam performs Salaah tranquility and properly making no mistake in Soorah Al-Faatihah (Opening Chapter of the Qur’aan) in a way that changes the meanings, he may join Salaah with this Imaam to attain the reward of congregational Salaah. Otherwise, he may wait for others to pray with to maintain the observance of Salaah in congregation, if possible... read more here.