The legend of the Seven Sleepers of Ephesus tells of the falling asleep of seven young men in a cave, who wake up after a great deal of time has passed.
The Seven Sleepers of Ephesus are viewed as saints by some Christians and Muslims.
The basic outline of the tale appears in Gregory of Tours (b. 538 - d. 594), and in Paul the Deacon's (b. 720 - d. 799) History of the Lombards. The best known version of the story appears in Jacobus de Voragine's Golden Legend.
Their story also appears in the Qur'an (Surah 18, verse 9-26) [1], which also includes a dog among the seven.