Surah Al-Kahf is the 18th chapter of the Holy Quran which mentions 4 stories about:

The People of Cave
The Companion of Two Gardens
Musa and Khidr
Dhul Qarnayn
There are many benefits to being familiar with Surah. The Prophet ﷺ said:

“One who memorized the first ten verses of Surah al Kahf will be secure against the Dajjal (Anti-Christ).” (Muslim)

It may seem that none of these stories are related to one another, but we see that the purpose or theme of all these stories is about Fitnah. Surah Al-Kahf explains Fitnah in different aspects of life.