People of the cave were old...
Al-Kāfi|Volume 8|Book 1|Chapter 594
عَلِيُّ بْنُ إِبْرَاهِيمَ رَفَعَهُ قَالَ قَالَ أَبُو عَبْدِ اللَّهِ (عليه السلام) لِرَجُلٍ مَا الْفَتَى عِنْدَكُمْ فَقَالَ لَهُ الشَّابُّ فَقَالَ لَا الْفَتَى الْمُؤْمِنُ إِنَّ أَصْحَابَ الْكَهْفِ كَانُوا شُيُوخاً فَسَمَّاهُمُ اللَّهُ عَزَّ وَ جَلَّ فِتْيَةً بِإِيمَانِهِمْ.
595. Ali Bin Ibrahim, by an unbroken chain, said: ‘Abu Abdullah عليه الصلاة والسلام said to a man: ‘What are considered to be the young ones (Al-Fati) among you?’ He said to him عليه الصلاة والسلام, ‘The youth’. So he عليه الصلاة والسلام said; ‘No! Al-Fati is the Believer. The Companions of the Cave (As’haab Al-Kahf) were old people, Allah عز وجل Mighty and Majestic Called them ‘Young men’ due to their belief’.
- Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (16/606)
- Ṣaḥīḥ al-Kāfī