Dūtajātaka

Suttapiṭaka · Khuddakanikāya · Jātaka (1) · Vol. 27 · Section 1781

[1781] Even though a person may think, "He is a kinsman, a friend, or a companion," one who formerly was good-hearted may afterwards turn into an enemy.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 27 · Section 1757 — Javanahaṁsajātaka