Surah 18. Al-Kahf, Ayah 21

I.e., by means of the legend which has grown up around the Men of the Cave and, more particularly, by means of the allegoric use which the Qur'an makes of this legend.

Lit., "given knowledge about them [to others]".

This, to my mind, is the meaning of the expression 'alayhim (lit., "over them") occurring here as well as in the subsequent reference to the building of a house of worship at the suggestion of those "whose opinion prevailed in the end" (alladhina ghalabu 'ala amrihim).

Lit., "debate their case (amrahum) among themselves": an indication of the fact that the legend of the Men of the Cave occupied men's minds for a long time, leading to many discussions and conflicting interpretations. The next sentence explains why God has "drawn [people's] attention" to this story in the context of the Qur'an.

 Their antique silver coins gave them away. People rushed to the cave to greet the youths, who finally passed away and were buried in the cave. The King decided to build a place of worship at the cave to commemorate their story.

 Some pagans suggested that a wall should be built to seal off the cave, whereas the believers decided to build a place of worship at the cave to honour those youths.

Thus: in this way, by these means, i.e., by the sending out of one of the Sleepers with the old money to the town to buy provisions. His old-fashioned dress, appearance, and speech, and the old uncurrent money which he brought, at once drew the attention of people to him. When they learnt his story, they realised that Allah, Who can protect His servants thus and raise them up from sleep after such a long time, has power to raise up men for the Resurrection, and that His promise of goodness and mercy to those who serve Him is true and was exemplified in this striking way. On the other hand, to the men of the Cave themselves, it became clear that Allah can change the situation before we are aware, and our hope in Him is not futile, and that even when we are on the brink of despair, a revolution is surely working in the world before the world itself realises it.

The perversity of man is such that as soon as ever a glimpse of truth becomes manifest, men fall into controversies about it. The Sleepers could not judge about the duration of their stay in the Cave, but they wisely left the matter and attended to the urgent business of their lives. The townsfolk could not agree as to the significance of the event; they fell to discussing immaterial details. What sort of a memorial should they raise?-a house or a place of worship or a tablet? The place of worship was built. But the real significance was missed until explained in the Qur-an.