Full Sharh — Riyad as-Salihin 120
وعن ابن عمر رضى الله عنهما قال: مررت على رسول الله صلى الله عليه وسلم وفى إزاري استرخاء، فقال: "يا عبد الله، ارفع إزارك" فرفعت ثم قال: "زد"، فزدت، فما زلت أتحراها بعد. فقال بعض القوم: إلى أين ؟ فقال: إلى أنصاف الساقين".((رواه مسلم))
English Translation
Ibn 'Umar (May Allah be pleased with them) reported:: My lower garment was trailing as I passed by the Messenger of Allah (ﷺ) so he said, "Raise your lower garment, Abdullah." I lifted it up and he told me to raise it higher. I complied with his orders and as I was still trying to find the best place (for it), one of the people asked where it should reach and he (ﷺ) replied, "Half way down the knees.".
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Dress
Hadith Number
120