{Did you think}—meaning: did you reckon—{that the companions of the Cave and the Inscription were, among Our signs, a wonder?} The interpretation of Qatada: he says, "There were among Our signs that which is more wonderful than that." The "kahf" (Cave) is the cave of the mountain, and the "raqim" (Inscription) is the valley in which the cave is located.
﴿أم حسبت﴾ أَيْ: أَفَحَسِبْتَ ﴿أَنَّ أَصْحَابَ الْكَهْفِ وَالرَّقِيمِ كَانُوا مِنْ آيَاتِنَا عَجَبًا﴾ تَفْسِيرُ قَتَادَةَ: يَقُولُ: قَدْ كَانَ فِي آيَاتِنَا مَا هُوَ أَعْجَبُ مِنْ ذَلِكَ، وَالْكَهْفُ: كَهْفُ الْجَبَلِ، وَالرَّقِيمُ: الْوَادِي الَّذِي فِيهِ الْكَهْفُ