One of the canonical readers of the Quran, Ḥamzah, often goes by the name Ḥamzah al-Zayyāt "Ḥamzah the oil salesman". But where did he get that name from?

al-ʿAskarī (d. 382 AH) relates a funny story about it, which suggests Ḥamzah recited the Quran from a written copy.

Ḥamzah was reading Sūrat al-Baqarah and arrived at http://quran.com/2/2  and read: ḏālika l-kitābu lā zayta fīhi "this is the book in which there is no oil" (instead of rayba "doubt"), to which his father told him to go learn recitation from the mouths of men of importance.

The story is probably apocryphal, but why would Ḥamzah have read rayba as a the nonsensical zayta? The suggestion is clearly that Ḥamzah was reciting the Quran from a manuscript, rather than from memory. Early manuscripts had little to no dotting, which leads to ambiguities.

By stroke of (bad) luck rayb 'doubt' and zayt 'oil' happen to have the exact same undotted consonantal skeleton. So when confronted with دلڪ الڪٮٮ لا رٮٮ ڡٮه, Ḥamzah apparently wasn't sure how to read رٮٮ, panicked and went for the hilariously wrong zayt 'oil' instead.