Had we sent down unto thee (Muhammad) (actual) writing upon parchment, so that they could feel it with their hands, those who disbelieve would have said: This is naught else than mere magic. They say: Why hath not an angel been sent down unto him? If We sent down an angel, then the matter would be judged; no further time would be allowed them for reflection

Surah Al Anaam, 'The Cattle', 6 : 7-8