سُورَةُ العَنكَبُوتِ
Al-Ankaboot·29:48
وَمَا كُنْتَ تَتْلُو مِنْ قَبْلِهِ مِنْ كِتَابٍ وَلَا تَخُطُّهُ بِيَمِينِكَ ۖ إِذًا لَارْتَابَ الْمُبْطِلُونَ٤٨
for, [O Muhammad,] thou hast never been able to recite any divine writ ere this one [was revealed], nor didst thou ever transcribe one with your own hand or else, they who try to disprove the truth [of thy revelation] might indeed have had cause to doubt [it].