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." (ID)
English reference (ID): Vol. 4, Book 32, Hadith 3581 (ID)
Arabic reference (ID): Book 32, Hadith 3712 (ID)