Woman uncovering part of her body in front of other women

As for the forearms, there is nothing wrong with uncovering
them in front of women, and there is also nothing wrong with showing the
neck and head in front of other women, but we offer some advice to our
womenfolk in the hope that Allaah may benefit them thereby. We say: the more
covering the clothes are, the better it is for them, and we tell them not to
follow whatever may be in these magazines and copy what is shown in them,
because that leads women to resemble kaafir women whether they want to or
not. The more covered women are, the better. Shaykh al-Islam Ibn Taymiyah
(may Allaah have mercy on him) stated that the women of the Sahaabah wore
garments that covered them from the hand to the ankle, and this is what is
best. There is nothing wrong if the calves show, but we are not suggesting
that she wear a dress that comes down only to the knees, because there may
be cause for concern about that, since may go further than that and shorten
their dresses to above the knee. But if a woman lifts up her garment to do
something and her sister sees her do that, there is nothing wrong with it.
But if the garment is designed to come down only to the knees, we do not
think that is right, rather we think that it should come down to the ankles.
End quote. 

Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on
him).