上行下效

lit. If the upper beam is not straight, the lower beam will be crooked (idiom); fig. subordinates imitate their superiors' vices

to set an example (idiom); to serve as a model

to teach by words and example (idiom)

teaching by example beats explaining in words (idiom); action speaks louder than words

to disrespect one's superiors; to offend one's elders

see a worthy, think to imitate (idiom, from Analects); emulate the virtuous; Follow the example of a virtuous and wise teacher.