Translation of the verse 48 from Surah Al-‘Ankabut : Number of verses 69 - - page 402 - Part 21.
Neither did you (O Muhammad SAW) read any book before it (this Quran), nor did you write any book (whatsoever) with your right hand. In that case, indeed, the followers of falsehood might have doubted.
And you did not recite before it any scripture, nor did you inscribe one with your right hand. Otherwise the falsifiers would have had [cause for] doubt.
(29:48) (O Prophet), you did not recite any Book before, nor did you write it down with your hand; for then the votaries of falsehood would have had a cause for doubt. *88
*88) This is the same argument that has already been given in Surahs Yunus and Qasas as a proof of the Holy Prophet's Prophethood. (See E.N. 21 of Yunus and E.N.'s 64 and 109 of AI-Qasas. For further explanation, see E.N. 107 of An-Nahl, E.N. 105 of Bani Isra'il, E.N. 66 of AI-Mu'minun, E.N. 12 of Al-Furqan, and E.N. 84 of Ash-Shu`araa). The basis of the argument in this verse is that the Holy Prophet was unlettered. His compatriots and his kinsmen among whom he had spent his whole life, from birth to old age, knew fully well that he had never read a book nor ever handled a pen. Presenting this actual fact Allah says: "This is a proof of the fact that the vast and deep knowledge of the teachings of the Divine Books, of the stories of the former Prophets, of the beliefs of the various religions and creeds, of the histories of the ancient nations, and the questions of social and moral and economic life, which is being presented through this ulettered, illiterate man could not have been attained by him through any means but Revelation. If he had been able to read and write and the people had seen him reading books and undertaking serious studies, the worshippers of falsehood could have had some basis for their doubts, that he had acquired the knowledge not through Revelation but through study and reading. But the fact of his being absolutely illiterate has left no basis whatever for any such doubt. Therefore, there can be no ground, except sheer stubbornness, which can be regarded as rational in any degree for denying his Prophethood."