Is it permissible for an employer to compel employees to swear on the Quran not to work in the same field after leaving their employment, and is expiation (kaffarah) obligatory for whoever breaks this oath?

The ruling on making employees swear an oath on the Qur'an not to work in the same field after leaving their employment is a subsidiary issue dependent on the permissibility of imposing such a condition. There is a significant difference of opinion among scholars regarding this, with the majority holding that the condition is not permissible.

It appears that such a condition should be avoided. If an employee swears an oath voluntarily, then if he wishes to work in the same field, he must expiate for his oath.