Sunan Ibn Majah, Volume 4, Book 32, Hadith 3580 (DarusSalam) ⓘ
It was narrated that Umm Salamah said: “The Messenger of Allah was asked about how long a woman’s hem should hang down. He said: ‘A hand span.’ I said: ‘But then (her legs and feet) will be uncovered.’ He said: ‘Then a forearm’s length, but no more than that.’”
حَدَّثَنَا أَبُو بَكْرٍ، حَدَّثَنَا الْمُعْتَمِرُ بْنُ سُلَيْمَانَ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنْ سُلَيْمَانَ بْنِ يَسَارٍ، عَنْ أُمِّ سَلَمَةَ، قَالَتْ سُئِلَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ كَمْ تَجُرُّ الْمَرْأَةُ مِنْ ذَيْلِهَا قَالَ " شِبْرًا " . قُلْتُ إِذًا يَنْكَشِفَ عَنْهَا . قَالَ ذِرَاعٌ لاَ تَزِيدُ عَلَيْهِ " .
also referenced under: Hadith 3580 (Reference) & Book 32, Hadith 3711 (In-Book)