The Prophet ﷺ said, "The lower garment should reach midway down the shin or to the ankles. There is no good in anything below that."
حدثنا أبو النضر حدثنا محمد يعني ابن طلحة عن حميد
عن النبي ﷺ قال الإزار إلى نصف الساق وإلى الكعبين لا خير في أسفل من ذلك
Its isnad is sahih. Muhammad bin Talha bin Musarrif is truthful, his hadith appears in Sahihayn and other collections, though there was some criticism of his memory. Haythami said in 5/122, "The men of Ahmad are the men of the sahih collection." The hadith was narrated by Bukhari, 10/256, number 5887, Fath al-Bari, in the Book of Clothing, "Whatever is below the ankles is in the fire." It has already occurred with Abu Hurairah in other wordings, 9896.