Abd al-Jabbar bin al-'Ala' عبد الجبار بن العلاء بن عبد الجبار · The Book of Adornment

"The Messenger of Allah said: 'The Izar should come to the middle of the shins and the calf. If you insist, then a little lower, and if you insist, then a little further down, but the Izar has no right to (come to) the ankle." This is the wordings of Muhammad.