It wasnarrated that 'Ali said:
"The Prophet (ﷺ) said to me: 'Donotshow your thigh, and do not look at the thigh of anyone, living ordead.'" (ID)
English reference (ID): Vol. 1, Book 6, Hadith 1460 (ID)
Arabic reference (ID): Book 6, Hadith 1527 (ID)