The Báb leaves the school of Shaykh Abid and becomes business associate with His uncle

At last His uncle was induced to take Him away from the school of Shaykh Abid, and to associate Him with himself in his own profession. There, too, He revealed signs of a power and greatness that few could approach and none could rival.

- Nabil (‘The Dawn-Breakers’, translated and edited by Shoghi Effendi)

The Báb left the school when He was thirteen years old

Siyyid ‘Alí-Muhammad [the Báb] had some six to seven years of schooling with Shaykh ‘Abid. In all probability He left the school… before He was thirteen. 

- Hand of the Cause Balyuzi ('The Báb - The Herald of the Day of Days')