Who are said here to "associate partners (with Allāh)"?

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

1. The Magians. [Ibn ʿAbbās, Ibn Qutaybah, al-Zajjāj]
2. The Arab polytheists. [Muqātil]