Hadith 223:8
Yahya ibn Sa'id narrated to us, from Sufyan, who said: Abu al-Zinad narrated to me, from Zur'ah ibn 'Abd al-Rahman ibn Jarhad, from his grandfather Jarhad, who said: The Messenger of Allah (peace and blessings of Allah be upon him) passed by while I had a garment on, and my thigh had become uncovered. He said: "Cover it, for the thigh is an 'awrah (intimate part)."
حدثنا يحيى بن سعيد، عن سفيان، قال: حدثني أبو الزناد، عن زرعة بن عبد الرحمن بن جرهد، عن جده جرهد، قال: مر رسول الله صلى الله عليه وسلم وعلي بردة، وقد انكشفت فخذي قال: " غط فإن الفخذ عورة "