Is the 'rasm' (orthography) of the Qur'an divinely ordained by the Prophet (peace be upon him)? What is the evidence for this, especially given the Prophet's illiteracy? And what is the wisdom behind the variation in the 'rasm' of some words, such as (ثم - thumma) in verse 67 of Surat Ghafir?

Scholars have differed on whether the Uthmani script (rasm al-Uthmani) for the Quran is divinely ordained (tawqifi) or a matter of scholarly discretion (ijtihadi). The majority view is that adherence to the Uthmani script is obligatory, and that maintaining it is preferable and more cautious, serving as proof against alteration and as a following of the predecessors (Salaf). Others, however, hold that it is permissible to write the Qurans with a script other than the Uthmani. As for the difference in writing the letter "mim" in the word "thumma" (then) with or without a tail, it has no relation to the Uthmani script; rather, it pertains to the calligrapher's taste and the type of script used.