Surah As-Saffat 37:45

يُطَافُ عَلَيْهِم بِكَأْسٍ مِّن مَّعِينٍۭ

There will be circulated among them a cup [of wine] from a flowing spring,

Translation: Saheeh International

Tafsir

they are served from all round each one of them is so served with a cup ka’san this denotes the vessel with the drink in it from a spring of wine that flows along the ground like streams of water

Excerpt from Tafsir al-Jalalayn, commentary on 37:45, via Quran.com. The reader has the full commentary and 9 more tafsirs.