Who are the "Ṣabiʾūn" mentioned in this āyah?

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

1. A group of Christians known to be very soft in speech, described as ascetics who shave the middle of their heads. [Ibn ʿAbbās]
2. A group between the Christians and Magians who do not follow any religion. [Mujāhid]
3. A group between the Jews and Christians. [Saʿīd ibn Jubayr]
4. A group resembling Magians. [Al-Ḥasan, al-Ḥakam]
5. They are a sect of the People of the Book who read the Psalms. [Abū al-ʿĀliyah]
6. They are a group who pray towards the qiblah, worship angels, and read the Psalms. [Qatādah]

7 .They are a group who say "There is no god but Allah" but do not have no (established form of) worship, no scripture, and no prophet. [Ibn Zayd]