Someone borrows a friend's book and promises to return it on Friday. The book is an entrusted item; returning it on the agreed day is a commitment. Keeping the book deliberately would betray trust; refusing without good reason to return it as promised would also break a commitment.
Lawful agreements should clarify duties, timing, and expectations. When circumstances change, informing the other party promptly is better than concealment or excuses.
The forceful wording لَا دِينَ emphasizes the seriousness of covenant-breaking. It should not be used as an instant verdict on a particular person's faith.