Safiyyah bint Abu Ubaid narrates: When the matter of the lower garment was mentioned, the noble wife of the Prophet, Lady Umm Salamah (may Allah be pleased with her), submitted to you: O Messenger of Allah (peace be upon him)! What is the ruling for a woman? The Prophet (peace be upon him) said: She should let it hang down a handspan. Lady Umm Salamah submitted: In that case, she will be uncovered. The Prophet (peace be upon him) said: Then let her hang it down a cubit (i.e., the length of both arms spread out), but she should not let it hang more than that.
Hadith Referenceصحیح ابن حبان / كتاب اللباس وآدابه / 5451
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «غاية المرام» (90)، «الصحيحة» (1864).فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم