Tafsir of Al-Kahf 18:95

(He said: "That in which my Lord has established me...") - [The verb is read] with idgham (assimilation), while Ibn Kathir and Humayd read it with fakk (disjunction/unassimilated). The meaning is: "That which my Lord has established me in" – meaning, He has made me established, capable, and powerful in terms of kingdom, wealth, and all other means.

"...is better" – meaning, than what you wish to offer me of tribute, for I have no need of it.

"...so help me with strength" – meaning, with whatever can be used to strengthen the effort toward the intended goal, such as tools, pieces of iron, or men, or that which is more general than both. The fa (so) is for inferring the command for assistance from the superiority of that which Allah, the Exalted, has established him in, compared to their wealth, or from his refusal to accept their tribute.

"...I will place between you and them" – the preposition of the adverbial phrase to the pronoun of those addressed precedes its addition to the pronoun of Gog and Magog, in order to manifest the utmost concern for their interests, just as they had observed in their statement: "between us and them."

"...a barrier" – meaning a fortified obstacle and a firm partition. It is greater than a sadd (dam/wall) and more secure. It is said: "A mardum garment," meaning one with patches upon patches; and it is said: "A mardum cloud," meaning thick and layered, one upon another. It is mentioned that its original meaning is filling a gap with stones or the like. It is also said that it means closing a breach absolutely; from this is the saying of Antarah: "Have the poets left any room for correction (mutaraddam)?" Then it was applied to what was mentioned. It is also said that it is synonymous with sadd (dam). The first view is supported by what Ibn Abi Hatim recorded from Ibn Abbas (may Allah be pleased with them both), that he said: "It is the strongest of barriers." Based on this, he has promised them the fulfillment of their request beyond what they had hoped for, which is befitting of the station of kings.