"Ibn Jarhad informed me from his father, that the Prophet ﷺ passed by him while his thigh was exposed, so the Prophet ﷺ said: 'Cover your thigh, for indeed it is 'Awrah.'"  

أَنَّ النَّبِيَّ ﷺ مَرَّ بِهِ وَهُوَ كَاشِفٌ عَنْ فَخِذِهِ فَقَالَ النَّبِيُّ ﷺ غَطِّ فَخِذَكَ فَإِنَّهَا مِنَ الْعَوْرَةِ  

[Machine] The Messenger of Allah ﷺ said, "Do not uncover your thigh, and do not look at the thigh of a living or dead person." This is from the statements of Hajjaj, and in the narration of Rawh, it is mentioned that the Messenger of Allah ﷺ came to me while I was uncovering my thigh, and he said, "O Ali, cover your thigh, as it is from the private areas."  

قَالَ رَسُولُ اللهِ ﷺ لَا تَكْشِفَ فَخِذَكَ وَلَا تَنْظُرْ إِلَى فَخِذِ حَيٍّ وَلَا مَيِّتٍ لَفْظُ حَدِيثِ حَجَّاجٍ وَفِي رِوَايَةِ رَوْحٍ قَالَ دَخَلَ عَلَيَّ رَسُولُ اللهِ ﷺ وَأَنَا كَاشِفٌ عَنْ فَخِذِي فَقَالَ يَا عَلِيُّ غَطِّ فَخِذَكَ فَإِنَّهَا مِنَ الْعَوْرَةِ