From: Rabbi Moshe Sofer
To: Rabbi Moshe Perles
The Chasam Sofer resolves a conceptual difficulty in Tosfos' derivation of a worker's right to retract from employment by citing the Ran's distinction: unlike an eved ivri seeking self-redemption, a regular worker requires no payment to walk away and is therefore not mechusar mamon. Applying this principle practically, he rules that a community's contractual clause requiring a departing rabbi to reimburse recruitment expenses recreates the impediment of mechusar mamon, binding the rabbi to his position and negating his right to retract even according to Tosfos.
Source: Shu"t Chasam Sofer CM §171