Hadithcore
Sahih al-Bukhari, 3849
sahih

Narrated `Amr bin Maimun:

During the pre-lslamic period of ignorance I saw a she-monkey surrounded by a number of monkeys. They were all stoning it, because it had committed illegal sexual intercourse. I too, stoned it along with them.

حَدَّثَنَا نُعَيْمُ بْنُ حَمَّادٍ، حَدَّثَنَا هُشَيْمٌ، عَنْ حُصَيْنٍ، عَنْ عَمْرِو بْنِ مَيْمُونٍ، قَالَ رَأَيْتُ فِي الْجَاهِلِيَّةِ قِرْدَةً اجْتَمَعَ عَلَيْهَا قِرَدَةٌ قَدْ زَنَتْ، فَرَجَمُوهَا فَرَجَمْتُهَا مَعَهُمْ‏.‏

References2 variants
In-Book Reference
Book 63, Hadith 74
USC-MSA web (English) reference
Vol. 5, Book 58, Hadith 188 (deprecated numbering scheme)