I said to Abu Saeed, "Did you hear anything from the Messenger of Allah ﷺ about the lower garment?"He replied, "Yes, I heard the Messenger of Allah ﷺ say, 'The believer's lower garment should reach the middle of his shins. There is no harm in it falling between that and the ankles, but whatever is below the ankles is in the Fire.' He said three times, 'Allah will not look at the one who drags his lower garment out of arrogance.'"
حدثنا علي بن محمد حدثنا سفيان بن عيينة
قلت لأبي سعيد هل سمعت من رسول الله ﷺ شيئا في الإزار قال نعم سمعت رسول الله ﷺ يقول إزرة المؤمن إلى أنصاف ساقيه لا جناح عليه ما بينه وبين الكعبين وما أسفل من الكعبين في النار يقول ثلاثا لا ينظر الله إلى من جر إزاره بطرا
[Its chain of transmission is sahih]. Abu Dawud narrated it in the chapter on clothing, section on the length of the lower garment, hadith no. 4093, from the hadith of Ala.