What is the ruling on one who vowed not to smoke shisha for the rest of his life, but then became unable to fulfill his vow?

Fulfilling a promise is a characteristic of believers, while breaking it is a characteristic of hypocrites. Fulfilling a promise made to Allah is more rightful and deserving, especially if the promise involves abandoning a sin, such as the forbidden act of smoking. A mere promise is not considered an oath that requires expiation unless it explicitly includes an oath by Allah.