The world forgetting by the world forgot.

Self note:

Masyaa Allaah, I have found a term in the Quran that also gives an idea of this line "The world forgetting by the world forgot" presented in 2 words "nasyan mansiyan"  (نسيًا منسيًا)

It is in surah Maryam (Mary) 19:21, while she was in the pangs of birth.  In translation, it just says "completely forgotten"  But the meaning of each word is much deeper than that

Nasiyan is to be in a state where one forgets.
Mansiyan is to be one who is forgotten.

- and I feel that the phrase is nicely described by that line mentioned above.