Language:
كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(44)
Chapter: The expedition of Mu`tah to the land of Syria
(44)
باب غَزْوَةُ مُوتَةَ مِنْ أَرْضِ الشَّأْمِ
Sahih al-Bukhari 4260

Narrated Nafi`:

Ibn `Umar informed me that on the day (of Mu'tah) he stood beside Ja`far who was dead (i.e. killed in the battle), and he counted fifty wounds in his body, caused by stabs or strokes, and none of those wounds was in his back.

حَدَّثَنَا أَحْمَدُ، حَدَّثَنَا ابْنُ وَهْبٍ، عَنْ عَمْرٍو، عَنِ ابْنِ أَبِي هِلاَلٍ، قَالَ وَأَخْبَرَنِي نَافِعٌ، أَنَّ ابْنَ عُمَرَ، أَخْبَرَهُ أَنَّهُ، وَقَفَ عَلَى جَعْفَرٍ يَوْمَئِذٍ وَهْوَ قَتِيلٌ، فَعَدَدْتُ بِهِ خَمْسِينَ بَيْنَ طَعْنَةٍ وَضَرْبَةٍ، لَيْسَ مِنْهَا شَىْءٌ فِي دُبُرِهِ‏.‏ يَعْنِي فِي ظَهْرِهِ‏.‏
Reference : Sahih al-Bukhari 4260
In-book reference : Book 64, Hadith 294
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 560
  (deprecated numbering scheme)