Tafsir Al-Jalalayn: Al-Kahf, Ayah 96

Bring me ingots of iron!’ namely pieces thereof as large as the blocks of stone to be used in the construction; he used these ingots in his construction placing between them firewood and coal. Until when he had levelled up the gap between the two flanks read al-sudufayn or al-sadafayn or al-sudfayn meaning the two flanks of the two mountains he set up bellows and lit a fire around this construction — he said ‘Blow!’ and they blew until when he had made it namely the iron a fire that is like a fire he said ‘Bring me molten copper to pour over it’ the two verbs ātūnī ‘bring me’ and ufrigh ‘pour’ are in contention over this direct object qitran ‘molten copper’; it this direct object has been omitted before the first verb because it is being governed by the second verb. Thus he poured the molten copper over the hot iron so that it penetrated between the individual ingots making a solid single whole.