Hadith 5445
Sayyiduna Hudhayfah (may Allah be pleased with him) narrates: The Prophet (peace and blessings of Allah be upon him) held my shin from the middle and said: This is the place for the lower garment; if you do not accept, then up to here, but the lower garment has no right below the ankles.
Hadith 5446
Ali bin Abdur Rahman narrates from his father: I presented myself before Sayyiduna Abu Saeed Khudri (may Allah be pleased with him). I asked: Have you heard the Prophet Muhammad (peace be upon him) say anything regarding the izar (lower garment)? He replied: Yes, I heard the Prophet Muhammad (peace be upon him) say: The izar of a believer should be till the middle of his shin. There is no harm if it is between the middle of the shin and the ankles, but whatever is below that will be in the Hellfire, and Allah Almighty will not look with mercy at the person who lets his izar hang out of pride.