Tafsir of An-Nisa' 4:169

(Except the path of Hell): This is because they possess no aptitude for guidance toward the truth and righteous deeds, which are the path to Paradise. The guidance understood from this exception—as noted by more than one scholar—refers by way of indication (isharah) to: His, Glory be to Him, creation of their evil deeds which lead them to Hell, in accordance with their predisposition; or it refers to driving them toward Hell on the Day of Resurrection by means of the angels.

Some have stated that the use of the word "guidance" here is sarcastic (tahakkum), unless what is intended is absolute indication, and the path is taken in its general sense. The exception is continuous.

(Forever): In the accusative case, functioning as an adverb of time (zarf), which removes the possibility that "eternity" (khulud) might be interpreted as a mere long duration.

(And that is [easy for Allah]): That is, the negation of His forgiveness and His guidance for them, and casting them into the Fire forever, is [easy for Allah]. There is nothing to divert Him from it. This serves to belittle their status and clarify that He, the Exalted, cares nothing for them and pays them no heed.