Shaykh Abu Abdir Rahmaan Yahyaa Bin Alee Al-Hajooree was asked:
Is it permissible to wear the Izaar until the knees while it is known the Sunnah is that which is between the middle of the leg and above the ankles?
The Sunnah in the clothing, whether it be an Izaar or a Qamees, is until the middle of the leg or above the ankles. And (as for) that which is lower than that (the ankles), then it is in the hellfire.
The prophet صلى الله عليه و سلم said:
“The Izaar of the believer is halfway below the knees”
The Izaar, if it’s worn halfway down the leg, it becomes beautiful. And, if it is lower than that towards the ankles, then it isn’t beautiful, and the best of guidance is the guidance of the prophet صلى الله عليه و سلم.
It being that it is raised until the knee, then this is exaggeration in raising it, it is overburdening oneself (and) not legislated, the truth is that which has preceded, thus (causing) no extremism nor negligence
[Al Kanzuthameen 4/167-168]
Majid Jawed Al-Afghanee