Thusajātaka

Suttapiṭaka · Khuddakanikāya · Jātaka (1) · Vol. 27 · Section 652

[652] It is said that a father monkey cut off with his teeth the manhood (phalaṃ, lit. "fruit") of his own son, born to him in the course of nature, while the son was still but young.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.