Hadithcore
Sahih al-Bukhari, 4260
sahih

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.‏

References2 variants
In-Book Reference
Book 64, Hadith 294
USC-MSA web (English) reference
Vol. 5, Book 59, Hadith 560 (deprecated numbering scheme)