As for the Mosque (Masjid) that they established over the People of the Cave, it is an indication of the obligation to veil them by establishing the Outward (Al-Zahir), similar to the indication of the Wall established by al-Khidr (peace be upon him) over the treasure. It is a sign that points to their gnosis, for it is a mark indicating them, yet none know them except for the few, and they are the believers. The Almighty commanded that we do not argue about them except with an apparent argument (mira’an zahiran); meaning, we do not reveal their inner gnosis. Nor should we consult any of the "People of the Outward" regarding them—meaning, we do not believe in what the exotericists say about them, and Allah knows best.

Similar to this is the saying of the Almighty in Surah Al-Mu’min: {And a believing man from the family of Pharaoh who concealed his faith said, "Do you kill a man [merely] because he says, 'My Lord is Allah' while he has brought you clear evidences from your Lord? And if he should be a liar, then upon him is his falsehood; but if he should be truthful, there will strike you some of what he promises you. Indeed, Allah does not guide one who is a transgressor and a liar."} (Ghafir: 28).

Reflect, O my brother, upon the meaning of this noble verse, which indicates the manner of concealing faith and manifesting Dissimulation for the purpose of teaching and discipline.