When the Prophet ﷺ said what he said about the lower garment, Umm Salama asked, "What about women?"He replied, "They may let it hang down a hand-span."She said, "Then their feet will be exposed."He said, "Then a forearm's length, but no more than that."
أخبرنا عبد الجبار بن العلاء بن عبد الجبار عن سفيان قال حدثني أيوب بن موسى عن نافع عن صفية
أن النبي ﷺ لما ذكر في الإزار ما ذكر قالت أم سلمة فكيف بالنساء قال يرخين شبرا قالت إذا تبدو أقدامهن قال فذراعا لا يزدن عليه
No references are available.
Its isnad is sahih. Abu Dawud transmitted it, Clothing, Chapter on the length of the train (of a garment), no. 4117, from the hadith of Nafi with this wording. Ibn Hibban graded it sahih, no. 1451, and it has other routes in Muslim and Tirmidhi, no. 1731, and others.