Hudhayfah said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) took hold of the muscle of my calf (or his calf) and said, ‘This is where the izaar should stop; if you insist, it may be lower, but it should not reach the ankles.’”
(Reported by al-Tirmidhi, who said this is a saheeh hasan hadeeth; see Sunan al-Tirmidhi, no. 1783)
Ibn ‘Umar said: “I passed by the Messenger of Allaah (peace and blessings of Allaah be upon him), and my izaar had slipped down. He said, ‘O ‘Abdullaah, pull up your izaar!’ so I pulled it up. He said, ‘More!’ so I pulled it up more, and always made sure it was pulled up properly after that.” Some people asked, “To where did you pull it up?” He said, “To mid-calf length.”
(Reported by Muslim, no. 2086; al-Dhahabi, Kitaab al-Kabaa’ir, 131-132)