The Koranic ummi was transformed into a claim of illiteracy centuries later

Evidence

It seems unlikely that the merchant Muhammad was in fact illiterate; early Hadîth describe him drawing up legal documents. For Goldfield, the Koranic ummiyyûn (plural of ummi) refers to those peoples who have not yet received divine scriptures; Muhammad was ummi, therefore, because he belonged to a people who had benefited from no previous revelation of scripture. However, from the third Muslim century onward, the predominant Muslim tradition is that ummi means illiterate. — John V. Tolan, Saracens, 1462

Categorization

• DEFINE: Explains the meaning shift of ummi from ‘people without scripture’ to ‘illiterate’.
• QUESTION: Who pushed the shift from ‘no previous scripture’ to ‘illiterate’ and what theological need did it serve — likely making Muhammad’s revelation purely miraculous/unlearned?