What is the definition of a promise in Islamic law? Is it linked to an oath or swearing? And is a person's failure to fulfill what they told another they would do considered a breach of promise and a sign of hypocrisy?

A promise is a pledge to do good in the future, and breaking it is the intentional failure to fulfill it without an excuse. A promise may be without an oath, but if an oath is taken upon it, it becomes confirmed and obligatory to fulfill. Scholars have agreed on the desirability of fulfilling promises, but they differed on its obligation. Imam Shafi'i, Imam Abu Hanifa, and the majority held that it is desirable, while a group maintained its obligation.