What were the reasons for the revelation of Surat Al-Kahf?

Surat Al-Kahf was revealed after a delegation from Quraysh asked the Prophet, peace and blessings be upon him, about three matters, guided by Jewish rabbis: the story of the young men of the cave, the account of Dhul-Qarnayn, and the nature of the soul. The revelation was delayed for fifteen days before Surat Al-Kahf was sent down, answering the questions about the young men and Dhul-Qarnayn, and gently reproaching the Prophet for his sadness over the delay in revelation.