Quran 6.9-11
Had we appointed him (Our messenger) an angel, We assuredly had made him (as) a man (that he might speak to men); and (thus) obscured for them (the truth) they (now) obscure. Messengers (of Allah) have been derided before thee, but that whereat they scoffed surrounded such of them as did deride. Say (unto the disbelievers): Travel in the land, and see the nature of the consequence for the rejecters!