al-Ṣaffāt

فَأَمَنُوا فَمَتَّعْنَاهُمْ إِلَي حِينٍ

148. “And they believed, so We gave them enjoyment for a while.”

Repentance for the past actions accompanied with sincere faith is a ground for the future success. Jonah’s people repented and Allah took back His Wrath and made them successful. So, this verse says:

Their beginning faith and repentance were formerly existed, but their detailed faith in Allah and His prophet Jonah and his teachings and instructions performed when Jonah (as) returned back among them. It is noteworthy that it is understood from the verses of the Qur’an that this second return has been toward that very former people and that some commentators have considered this return as a new duty for him does not adopt to the verses of the Qur’an, because from one side, we recite here that these people, whom Jonah was appointed to guide, believed and Allah gave them enjoyment for a certain time.

This makes it clear that the purpose of ‘for a while’ is the same as the end of their life and their natural death. There is a question that why in the previous verses it has been said ‘a hundred thousand people or more’ the apparent state is that these kinds of meanings are for emphasis and the greatness of something, not for the sake of the doubt of the speaker.