The tradition of the Seven Sleepers exists in both Christian and Muslim (ashab al kahf, “people of the cave”) tradition.
The Islamic version of the legend of the Young Sleepers is well known in the Muslim world as it is quoted in the Qur’an in Surah 18:9-26. In this version, the exact number of sleepers is not given and is known only to Allah. The legend speaks of young men who slept for 300 or 309 solar years. In the Islamic version of the legend there is also a faithful dog that accompanied the young men on their way to the cave and slept at its entry. People passing nearby saw the sleeping dog and were afraid to look inside because they thought it was guarding the cave’s secrets. The young men are known as the “people of the cave.”
The Christian version tells the story of seven young men who were accused of belonging to the Christian community at the time of the persecutions by the Roman Emperor Trajan Decius, who reigned in AD 249-251. At this time, a group of young Christian men fled from the city and hid in a cave. When they were found sleeping in the cave, at the behest of the emperor the entrance was sealed. Many years passed and from a persecuted religion Christianity became the official state religion. After over 250 years, during the reign of Theodosius II (AD 408-450), a landowner decided to demolish the walled-up cave entrance. He was genuinely surprised to find seven men sleeping inside. They woke up with the conviction that they had been sleeping for just a day.