If I made a vow and did not fulfill it, do I owe expiation?

Fulfilling a promise is recommended (mustahabb) and not obligatory (wajib) according to the majority of scholars. One who fails to fulfill it incurs no sin or expiation, but rather has committed something disliked (makruh) in a minor sense (karahah tanzih). Some scholars, however, are of the view that fulfilling it becomes binding if failure to do so results in harm to the one to whom the promise was made.