Tafsir of Al-Insan 76:15

"And there will be circulated among them vessels" — the plural of ina' (vessel), similar to kisa' (garment) and aksiya (garments), which refers to that in which a thing is placed. Awani (vessels) is the plural of the plural.

"...of silver" — and akwab (cups), which is the plural of kub (cup). A kub is a drinking vessel that has no handle, as Al-Raghib stated. In al-Qamus, it is defined as a jug that has no handle or no spout. It has also been said that it is a large jug that has neither a narrow opening nor a handle.

"...that were..." — meaning those cups.

"...crystal-clear" (qawarira) — the plural of qarura, which is a thin vessel made of glass in which drinks are placed. Its grammatical state is an accusative of state (hal). If [the verb] is taken as complete, it is as if you were to say: "they are crystal-clear." And His saying, the Exalted: [continues...].