Sahih Muslim Book - 49, Hadith - 7023

حَدَّثَنِى زُهَيْرُ بْنُ حَرْبٍ حَدَّثَنَا عَفَّانُ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ أَخْبَرَنَا ثَابِتٌ عَنْ أَنَسٍ أَنَّ رَجُلاً كَانَ يُتَّهَمُ بِأُمِّ وَلَدِ رَسُولِ اللَّهِ -صلى الله عليه وسلم- فَقَالَ رَسُولُ اللَّهِ -صلى الله عليه وسلم- لِعَلِىٍّ « اذْهَبْ فَاضْرِبْ عُنُقَهُ ». فَأَتَاهُ عَلِىٌّ فَإِذَا هُوَ فِى رَكِىٍّ يَتَبَرَّدُ فِيهَا فَقَالَ لَهُ عَلِىٌّ اخْرُجْ. فَنَاوَلَهُ يَدَهُ فَأَخْرَجَهُ فَإِذَا هُوَ مَجْبُوبٌ لَيْسَ لَهُ ذَكَرٌ فَكَفَّ عَلِىٌّ عَنْهُ ثُمَّ أَتَى النَّبِىَّ -صلى الله عليه وسلم- فَقَالَ يَا رَسُولَ اللَّهِ إِنَّهُ لَمَجْبُوبٌ مَا لَهُ ذَكَرٌ.

It was narrated from Anas that a man was accused of misbehaving with the concubine of the Messenger of Allah (s.a.w)who had borne him a child. The Messenger of Allah (s.a.w) said to 'Ali: "Go and strike his neck." 'Ali came to him and found him in a well, cooling himself off. 'Ali said to him: "Come out," and he took him by the hand and brought him out. Then he saw that he was mutilated and did not have a penis, so he refrained from killing him. Then he came to the Prophet (s.a.w) and said: "O Messenger of Allah, he is mutilated, he does not have a penis."