It wasnarrated from Ibn 'Umar:
"The wives of the Prophet (ﷺ) wereallowed to let their hems hang down, so they used to come to us andwewould measure one forearms length for them with a reed." (FR)
English reference (FR): Vol. 4, Book 32, Hadith 3581 (FR)
Arabic reference (FR): Book 32, Hadith 3712 (FR)