Who would "judge between mankind" according to this?

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

1. It is Allah.
2. It is the Prophet to whom the Book was revealed.
3. It is the Book itself, as in the verse "This is Our Book; it speaks against you with truth" (45:29).