First: The school of Abū Ḥanīfah
Imām Muḥammad b. al-Ḥasan states in his recension of the Muwaṭṭaʾ (p. 205, with the Indian edition of al-Taʿlīq al-Mumajjad):
“A woman in iḥrām should not wear the niqab; but if she wishes to cover her face, let her lower a piece of cloth so that it hangs down from the top of her khimār. This is the view of Abū Ḥanīfah and the majority of our jurists.”

Abū Jaʿfar al-Ṭaḥāwī says in Sharḥ Maʿānī al-Āthār (2/392–393):
“It is permissible for people to look at what is not forbidden of women who are unrelated to them—that is, at their faces and hands—whereas this was forbidden with respect to the wives of the Prophet ﷺ. This is the opinion of Abū Ḥanīfah, Abū Yūsuf, and Muḥammad, may Allah have mercy on them.”

Second: The school of Mālik
His disciple ʿAbd al-Raḥmān b. al-Qāsim al-Miṣrī narrates in the Mudawwanah (2/221) something similar to Imām Muḥammad’s statement regarding the muḥrimah who wishes to let a veil hang over her face, adding by way of clarification:
“If she does not intend to cover herself, she should not let it hang down.”

Ibn ʿAbd al-Barr transmitted this in al-Tamhīd (15/111) and approved it. After citing the explanation of Ibn ʿAbbās and Ibn ʿUmar for the verse: “except what ordinarily appears thereof,” ⦗34⦘