an.3.114 Aṅguttara Nikāya (Numbered Discourses)

Rare

“Mendicants, the appearance of three people is rare in the world.
What three?
A Realized One, a perfected one, a fully awakened Buddha. A person who teaches the teaching and training proclaimed by a Realized One. A person who is grateful and thankful.
The appearance of these three people is rare in the world.”