The Eye
Cakkhu Sutta  (SN 25:1)

Near Sāvatthī. “Monks, the eye is inconstant, changeable, alterable. The ear… The nose… The tongue… The body… The mind is inconstant, changeable, alterable.

“One who has conviction & belief that these phenomena are this way is called a faith-follower: one who has entered the orderliness of rightness, entered the plane of people of integrity, transcended the plane of the run-of-the-mill. He is incapable of doing any deed by which he might be reborn in hell, in the animal womb, or in the realm of hungry ghosts. He is incapable of passing away until he has realized the fruit of stream-entry.

“One who, after pondering with a modicum of discernment, has accepted that these phenomena are this way is called a Dhamma-follower: one who has entered the orderliness of rightness, entered the plane of people of integrity, transcended the plane of the run-of-the-mill. He is incapable of doing any deed by which he might be reborn in hell, in the animal womb, or in the realm of hungry ghosts. He is incapable of passing away until he has realized the fruit of stream-entry.

“One who knows and sees that these phenomena are this way is called a stream-enterer, steadfast, never again destined for states of woe, headed for self-awakening.”

See also: MN 70