Tafsir of Al-Mutaffifeen 83:27

"And its mixture is from Tasnim" is a conjunctive clause linked to "its seal is musk," serving as another description of the Rahiq (pure nectar), similar to the former. What lies between them is a parenthetical statement confirming its preciousness.

Tasnim is a proper noun for a specific spring in Paradise, as narrated from Ibn Mas‘ud. Hudhayfah al-Yaman said: "It is a spring from the highest level (of Paradise)." It was named Tasnim, which is the verbal noun derived from sannama—meaning "he raised it"—either because its drink is the loftiest drink in Paradise, as narrated from Ibn Abbas, or because it comes to them from above, as narrated from al-Kalbi. It is also reported that it flows through the air, elevated (arching), until it pours into their vessels. It has been said that it was named as such because of the high status of those who drink from it.

The fact that it is a proper noun for what has been mentioned does not necessitate its being indeclinable (ghayr munsarif) due to the factors of being a proper name and feminine; for the word 'ayn (spring) is feminine, yet it may be treated as masculine based on the interpretation of "water" or similar concepts.

The particle min (from) may be bayaniyyah (explanatory) or tab'idiyyah (partitive), meaning: that with which the Rahiq is mixed is Tasnim—that is, the water of that spring, or a portion thereof. It is also permissible for it to be ibtida’iyyah (denoting source/origin).