"The Messenger of Allah (ﷺ) took hold of the calf of my shin - or his shin - and he said: "This is the place of the Izar, if you must lower it, then the Izar has no right to be on the ankles."

This Hadith is Hasan Sahih. Ath-Thawri and Shu'bah reported it from Abu Ishaq.

Jami` at-Tirmidhi Book 24, Hadith 72