Surah 26. Ash-Shuara, Ayah 199

As the Qur'an points out in many places, most of the Meccan contemporaries of Muhammad refused in the beginning to believe in his prophethood on the ground that God could not have entrusted "a man from among themselves" with His message: and this in spite of the fact that the Qur'an was expressed "in the clear Arabic tongue", which they could fully understand: but (so the argument goes) if the Prophet had been a foreigner, and his message expressed in a non-Arabic tongue, they would have been even less prepared to accept it- for then they would have had the legitimate excuse that they were unable to understand it (cf. 41:44 ).

The turn of Arabia having come for receiving Allah's Revelation, as was foretold in previous Revelations, it was inevitable that it should be in the Arab tongue through the mouth of an Arab. Otherwise it would have been unintelligible, and the Arabs could not have received the Faith and become the vehicles for its promulgation as actually happened in history.