It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that when the Messenger of Allah (peace and blessings be upon him) said what he said about the hem of the garment, Sayyidah Umm Salamah (may Allah be pleased with her) said: What is the ruling for us? He (peace and blessings be upon him) said: "Let it trail a hand-span." She said: Then both feet would be exposed. He (peace and blessings be upon him) said: "Let it trail a forearm's length."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20310