There are several ancient poems about being polite to people, just three.

"A good word warms three winters, and a bad word hurts the cold in June."

Obedience is better than obedience, training is better than obedience. -Songshi Zanning

Courtesy is not close to flattery, but harmony is not flowing. —— Xue Mingxuan

Gaoding's "Country House"

The shepherd boy fell into his arms when he saw the guest worship. The cows hurried home during the day, and the wind and rain in Qianxi were bad.