an.3.85 Aṅguttara Nikāya (Numbered Discourses)

A Trainee

Then a mendicant went up to the Buddha, bowed, sat down to one side, and said to him:
“Sir, they speak of this person called ‘a trainee’.
How is a trainee defined?”
“They train, mendicant, that’s why they’re called ‘a trainee’.
What is their training?
They train in the higher ethics, the higher mind, and the higher wisdom.
They train, that’s why they’re called ‘a trainee’.
As a trainee trains,
following the straight road,
first they know about ending;
enlightenment follows in the same lifetime.
Then the knowledge comes
such a one, freed through enlightenment,
with the end of the fetters of rebirth:
‘My freedom is unshakable.’”