Most scholars hold this view, and they are unanimously agreed that a woman uncovers her face in prayer and during iḥrām. Abū Bakr ibn ʿAbd al-Raḥmān ibn al-Ḥārith said, “Every part of a woman—even the tip of her fingernail—is ʿawrah.”
Then Ibn ʿAbd al-Barr said:
“This statement lies outside the recognised positions of the scholars, for the scholars have unanimously agreed that a woman may perform the obligatory prayer with her hands and face uncovered; all of these parts in fact touch the ground in prostration. They have also agreed that she does not pray while veiled and that she is not required to wear gloves during the prayer. (1) In this there is the clearest proof that those parts are not ʿawrah and that anyone may look at them provided he does so without desire or impropriety. As for looking with lust, that is forbidden: if gazing at her from above her clothing with desire is unlawful, then how much more so is looking at her unveiled face. A statement similar to that of Abū Bakr has been reported from Aḥmad ibn Ḥanbal. (2)"