Hadithcore
Sahih Muslim, 338 b
sahih

This hadith has been narrated by Ibn Abu Fudaik and Dabbik b. 'Uthman with the same chain of transmitters and they observed:

Private parts of man are the nakedness (which is concealed).

وَحَدَّثَنِيهِ هَارُونُ بْنُ عَبْدِ اللَّهِ، وَمُحَمَّدُ بْنُ رَافِعٍ، قَالاَ حَدَّثَنَا ابْنُ أَبِي فُدَيْكٍ، أَخْبَرَنَا الضَّحَّاكُ بْنُ عُثْمَانَ، بِهَذَا الإِسْنَادِ وَقَالاَ - مَكَانَ عَوْرَةِ - عُرْيَةِ الرَّجُلِ وَعُرْيَةِ الْمَرْأَةِ ‏.‏

References2 variants
In-Book Reference
Book 3, Hadith 91
USC-MSA web (English) reference
Book 3, Hadith 668 (deprecated numbering scheme)