What does "it" in the "dwelling in it forever" refer to?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. It refers to the curse. [Ibn Masʿūd, Muqātil]
2. It refers to the Fire. Even though it has not been mentioned explicitly, it is understood.