"And if you are in doubt concerning that which We have sent down (i.e. the Qur'an) to Muhammad then produce a Surah (chapter) of the like thereof and call your witnesses (supporters and helpers) besides Allah, if you are truthful."
Quran 2.23

"Aur agar tumhe is kalaam(Quran) mai shak hai joh humne apne bande(Muhammad sallallahu alaihi wa sallam) par utara toh is jaise ek surat le aao, aur bula laao apne madadgar Allah ke siwa agar tum sachche ho."
Quran 2.23
Surah Baqarah