Gratitude
Kataññu Suttas  (AN 2:31–32)

“Monks, I will teach you the level of a person of no integrity and the level of a person of integrity. Listen & pay close attention. I will speak.”

“As you say, lord,” the monks responded to him.

The Blessed One said, “Now what is the level of a person of no integrity? A person of no integrity is ungrateful & unthankful. This ingratitude, this lack of thankfulness, is advocated by rude people. It is entirely on the level of people of no integrity. A person of integrity is grateful & thankful. This gratitude, this thankfulness, is advocated by civil people. It is entirely on the level of people of integrity.”

“I tell you, monks, there are two people who are not easy to repay. Which two?

Your mother & father. Even if you were to carry your mother on one shoulder & your father on the other shoulder for 100 years, and were to look after them by anointing, massaging, bathing, & rubbing their limbs, and they were to defecate & urinate right there [on your shoulders], you would not in that way pay or repay your parents. If you were to establish your mother & father in absolute sovereignty over this great earth, abounding in the seven treasures, you would not in that way pay or repay your parents. Why is that? Mother & father do much for their children. They care for them, they nourish them, they introduce them to this world. But anyone who rouses his unbelieving mother & father, settles & establishes them in conviction; rouses his unvirtuous mother & father, settles & establishes them in virtue; rouses his stingy mother & father, settles & establishes them in generosity; rouses his foolish mother & father, settles & establishes them in discernment: To this extent one pays & repays one’s mother & father.“

See also: MN 110; SN 7:14; AN 2:118; AN 4:32; AN 4:73; Iti 106