Ashab-e-Kahf or the people of Kahf; Their story is told in Quran in Surat Al-Kahf (18). These were a few young men, believers of Allah. Their people did not believe in Allah and according to some tafaseer, their people worshiped fire. These brave young believers declared their faith in the court of the non-believer king. When they saw how outnumbered they were and nobody was supporting them, they took refuge in a cave. Kahf is the name of the mountain of the cave they took refuge in.Allah made them all(along their dog) go into a very long sleep.
“We narrate unto you (O Muhammad SAW) their story with truth: Truly! They were young men who believed in their Lord (Allâh), and We increased them in guidance.” (13)
And We made their hearts firm and strong (with the light of Faith in Allâh and bestowed upon them patience to bear the separation of their kith and kin and dwellings, etc.) when they stood up and said: “Our Lord is the Lord of the heavens and the earth, never shall we call upon any ilâh (god) other than Him; if we did, we should indeed have uttered an enormity in disbelief.” (14)
“These our people have taken for worship âliha (gods) other than Him (Allâh). Why do they not bring for them a clear authority? And who does more wrong than he who invents a lie against Allâh.” (15)
“(The young men said to one another): “And when you withdraw from them, and that which they worship, except Allâh, then seek refuge in the Cave, your Lord will open a way for you from His Mercy and will make easy for you your affair (i.e. will give you what you will need of provision, dwelling, etc.).” (16)
Allah made arrangements for their safety,and they received proper sunlight and fresh air.
“And you might have seen the sun, when it rose, declining to the right from their Cave, and when it set, turning away from them to the left, while they lay in the midst of the Cave. That is (one) of the Ayât (proofs, evidences, signs) of Allâh. He whom Allâh guides, is rightly guided; but he whom He sends astray, for him you will find no Walî (guiding friend) to lead him (to the right Path).”(17)
“And you would have thought them awake, while they were asleep. And We turned them on their right and on their left sides, and their dog stretching forth his two forelegs at the entrance [of the Cave or in the space near to the entrance of the Cave (as a guard at the gate)]. Had you looked at them, you would certainly have turned back from them in flight, and would certainly have been filled with awe of them.” (18)