It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that when the Prophet (peace and blessings be upon him) said what he said about the waist-wrapper (izar), Sayyidah Umm Salamah (may Allah be pleased with her) said: O Messenger of Allah! What should women do? He (peace and blessings be upon him) said: "They should let it hang down a hand-span." She said: Then their feet would be exposed. He (peace and blessings be upon him) said: "Then a forearm's length; they should not exceed it."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20309