させる ⇒ さすTo make someone do something (causative)

The auxiliary verbs せる and させる will be modified in 関西弁(かんさいべん), creating a new form that interacts with the indeterminate form of verbs. In the case of う - Verbs, this is the form that interacts with ない, not the form that interacts with う. In standard Japanese, the せる and させる forms are referred to as 'causative' (someone/thing is made to perform an action). This meaning stays the same in the Kansai dialect.

The kansai form of せる will be す (with う - Verbs), while させる will become さす (with る - Verbs, する, and くる).

Caution

These short forms of せる and させる are 'preferred' in the Kansai dialect, but are not a requirement. The standard forms may still occasionally be heard.