Our advice is that women should not wear trousers
Our advice is that women should not wear trousers because this is the dress of kaafir women, so they should not wear them.
A woman should only wear women’s clothes, the dress of her own country; she should not deviate from that.
She should strive to wear concealing and modest clothes which are not tight or see-through, but which cover her and do not show the shape of the body, and which do not resemble the clothes of the kuffaar or of men, or a dress of fame and vanity.
Majmoo’ Fataawa wa Maqaalaat Mutanawwi’ah li Samaahat al-Shaykh al-‘Allaamah ‘Abd al-‘Azeez ibn ‘Abd-Allaah ibn Baaz (may Allaah have mercy on him), vol. 9, p. 43