Tafsir of Al-Waqi'ah 56:19

"La yusadda'una 'anha" (They will not be affected by headache therefrom): That is, because of it. Its literal meaning is that their headache does not originate from it. The intended meaning is that no headache will afflict their heads due to any hangover resulting from it, as is the case with the wines of this world.

It is also said: "They will not be separated from it," meaning their pleasure will not be interrupted for any reason, as those who drink the wines of this world are separated by various causes of disruption.

Mujahid recited it as "La yusadda'una" with the ya opened and the sad geminated (tashdid), on the basis that its origin is yata-sadda'una (they separate/scatter), whereby the ta is assimilated into the sad; meaning, they will not be dispersed, similar to the Almighty's saying: "On that day, they will be separated" (yussadda'una), with the ya opened and the sad lightened—meaning: they will not be separated by one another, nor will they be dispersed, such that one of them would sit between two others and separate those who are close; for such an act is a lack of manners and is not part of good fellowship.

"Wa la yunzifun" (And they will not be intoxicated/depleted):

Mujahid, Qatadah, and al-Dahhak said: Their minds will not be lost due to intoxication, derived from nazafa al-sharib (the drinker became drunk), meaning when his mind is gone; the drunkard is called nazif and manzuf.

It is also said: It is derived from nazafa al-ma' (to drain water), meaning to draw it from the well bit by bit; thus, the speech is based on the estimation of an omitted genitive.

Ibn Abi Ishaq, ‘Abdullah, al-Sulami, al-Jahdari, al-A'mash, Talhah, ‘Isa, and ‘Asim—as related from him by ‘Abd ibn Humayd—recited it as wa la yunzifuna (with the ya vocalized with damma and the za with kasra), from the phrase anzafa al-sharib when his mind or his drink is exhausted. Its meaning is: "He has reached a state of depletion." Its parallel is aqsha'a al-sarab (the mirage faded) and qasha'athu al-rih (the wind dispersed it); its true meaning is that it entered into the state of fading.

Ibn Abi Ishaq also recited it as wa la yunzifuna (with the ya vocalized with fatha and the za with kasra). It is stated in al-Majma' that this is interpreted to mean that their wine will not run out.

The correlation between the two clauses, according to the reading of the majority as you have heard regarding them, is that the first is to explain the negation of harm to the physical bodies, and the second is to explain the negation of harm to the minds. Reflect upon this to understand it, if Allah the Almighty wills, regarding what is other than that.