The Iranian Shi’ite scholar Ali Dashti writes (in his book Twenty Three years – A study of the prophetic career of Mohammad), “The Quran contains sentences which are incomplete and not fully intelligible without the aid of commentaries; foreign words, unfamiliar Arabic words, and words used other than the normal meaning; adjectives and verbs infected without observance of the concord of gender and number; illogical and ungrammatically applied pronouns which sometimes have no referent; and predicates which in rhymed passages are often remote from subjects.”
He contends that the Quran possesses numerous grammatical irregularities. Dashti notes that in verse 9 of surah 49, “If two parties of believers have started to fight each other, make peace between them”, the verb meaning “have started to fight” is in the plural, whereas it ought to be in the dual like its subject “two parties”.
Dr Anis A. Shorrosh, who is a Palestine Arab, points out that in 2:177, the word “Sabireen” in Arabic should have been “Sabiroon” because of its position in the sentence. Likewise, “Sabieen” is more correct Arabic than “Sabioon” in 5:69. Shorrosh also notes that there is a gross error in Arabic in 3:59.
Muslim response : The Qur’an being one of the major source materials of the grammarians’ works can obviously not be judged on the basis of the grammarians’ work. Had the position of the Qur’an as a source material of the compiled Arabic grammar been fully appreciated, it would have been more appropriate and understandable if someone had challenged the accuracy and comprehensiveness of the grammarians’ work, rather than challenge the reliability of the Qur’an, when and if an inexplicable deviation was/is found in the Qur’an.
Christian response : It is true that the Quran is a major source of study of Arabian grammar. But Arabic was an established language long before the Quran even came about. Therefore when Muhammad introduced the Quran and claim that it is a literary masterpiece, and one still finds gramatically irregularities compared with what was spoken then and what is spoken now, in accordance with gramatical rules, then something is wrong. Adopting the reasoning above is a blind faith situation. You want to believe that the Quran is a literary masterpiece. So if the Quran has zero gramatical errors, you would say that that is proof that it is a literary masterpiece. If it contains gramatical errors, you would still insist that it is a materpiece and all other grammar is wrong and should be judged based on the Quran instead.