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).