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 shine own hand
46 -or else. they who try to disprove the truth [of thy revelation]
47 might indeed have had cause to doubt [it].
Asad Translation Note Number :
Lit., "with thy right hand" - the term yamin being used here metonymically, denoting no more than one's "own hand". - It is historically established that Muhammad, the "unlettered prophet" (cf. 7:157 and {158}), could neither read nor write, and could not, therefore, have derived his extensive knowledge of the contents of earlier revelations from the Bible or other scriptures: which - as the Qur'an points out - ought to convince any unprejudiced person that this knowledge must have come to him through divine revelation.
The participial noun mubtil is derived from the verb abtala, "he made a false [or "vain"] claim", or "tried to disprove the truth [of something]", or "to reduce [something] to nothing", or "to prove [it] to be of no account", or "null and void", or "unfounded", "false", "spurious", etc., irrespective of whether the object is true or false, authentic or spurious, valid or unfounded (Lisan al-'Arab and Taj al-'Arus).