Is it permissible for non-Muslim women to look at a Muslim woman without hijab, and what is the evidence for that?

Scholarly opinions vary regarding the permissibility of a non-Muslim woman looking at a Muslim woman without hijab, with some deeming it permissible based on several pieces of evidence. Nevertheless, a Muslim woman must be cautious of an untrustworthy non-Muslim woman who might describe her or malign her, by either wearing hijab or avoiding her company. For one who chooses to be cautious regarding her religion and observes hijab in front of non-Muslim women, her action is good and she will be rewarded for it. However, she should not condemn those who differ with her on this matter, as it is an issue of ijtihad (independent reasoning). Furthermore, women in general should not be overly revealing except for what is normally visible, such as the hands, feet, neck, and hair, and modesty is a branch of faith.