Praying behind Imaam who prays quickly and makes mistakes in his recitation
7-6-2016 | IslamWeb
Question:
Assalamu alaykum. Please give me a quick response. At work, we, around 30 men, make congregation for the Maghrib prayer in the office prayer room. The problem, however, is that the regular imam prays very fast, and his recitation also contains some major mistakes. Besides him, though, there is another man who prays moderately and whose recitation is good. However, if that person is selected to lead, then he has to do a congregational supplication after the prayer as this is a custom in our country. Without doing a congregational supplication after the prayer, he cannot be selected as an imam. Now, is it allowed for him to lead the congregation properly and make the congregational supplication for the sake of choosing the lesser harm? Note that he will simply raise his hand after the prayer as if he is making a congregational supplication while actually intending supplication by himself without intending to supplicate in congregation.
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad 
is His slave and Messenger.
As for the first person, of whom you mentioned that he makes mistakes in his recitation and prays fast, then some details have to be mentioned about his ruling:
1- If he makes mistakes in Al-Faatihah (the Opening Chapter of the Quran) in a way that he drops a letter from it, for example, or he makes a mistake that changes the meaning, then the prayer behind such a person is not valid for those who can recite it properly. An-Nawawi 
said in Sharh al-Muhaththab, “It is obligatory to recite Al-Faatihah in prayer with all its letters and double letters [the Arabic Shaddah], which [double letters] are fourteen; and if he drops a letter from them or does not pronounce the double letter as it should be pronounced [i.e. with Shaddah] or that he changes a letter with another letter while he can recite properly, then the prayer behind him is not valid.”
Also, the Kuwaiti Fiqh Encyclopedia reads, “It is not valid for an ummi imaam (who cannot recite Al-Faatihah properly) to lead a person who can recite properly; and it is not valid for a dumb person to lead a person who can recite or an ummi person in prayer because the recitation is an intended pillar in prayer, so it is not valid for a person who can fulfill this pillar to be led by someone who is unable to fulfill it, and (this is so) because the imaam bears responsibility for recitation on behalf of the people led in prayer, and this cannot be done by an ummi person.”
2- If the mistake is made in reciting a chapter other than Al-Faatihah, or the mistake is in Al-Faatihah but it is a mistake that does not change the meaning, then the prayer behind such a person is valid.
With regard to praying fast, if this does not affect the tranquility in prayer, then this does not invalidate the prayer, but if this imaam does not achieve tranquility (Tuma’neenah) in fulfilling the pillars of the prayer, then the prayer behind him is not sufficient. Tuma’neenah is that the limbs (body parts) of the praying person become still (after moving from one position of prayer to another) even if for a short while. Al-Mardaawi said, “There is no difference of opinion about the obligation of fulfilling tranquility in these movements; this is achieved by the limbs resting in their new position, even it were for a short while, according to the correct view of the scholars...” For more benefit, please refer to fatwa 180233.
As regards the other imaam, who recites well and does not pray fast, then it is valid that he leads the prayer. The congregational Du’aa (supplication) that he says after the obligatory prayer does not invalidate it. However, he should stop making it regularly because it is an innovation (Bid'ah) as stated by some scholars.
The fatwa of Shaykh Ibn Taymiyyah reads:
“Performing an act in the congregational prayers other than the legislated Sunan, like the athaan in ‘Eed al-Fitr and ‘Eed al-Adh-ha, and Qunoot supplication in the five daily prayers, and the congregational Du’aa after the five daily prayers, or the congregational Du’aa in Fajr and ‘Asr, and to seclude oneself in one’s local mosque for the purpose of worship on the day of ‘Arafah, or to gather regularly to perform a supererogatory prayer, or recitation, or Thikr (mention of Allaah) every night; and so on is Bid'ah because making what is not a Sunnah resemble the Sunnah is a detestable innovation, as proven by the Quran, the Sunnah, the statements of the righteous predecessors, and Qiyaas (analogy)."
For more benefit, please refer to fataawa 88520and 196517.
Allaah knows best.