Yesh adesh ! Yesh upadesh!--This is the rule !This is the teaching--From Taittiriyoupanishad.

We have in the Taittriya Upanishad a valedictory exhortation which reveals to us something of the system of education that produced the cultured among the ancient inhabitants of this sacred land.

After having taught the Vedas the teacher instructs the pupil thus...

"Speak what is true:Do your duties.Continue without neglect the daily study of the Veda.Now that you have come to the end of your stay with your teacher ,marry and bring forth progeny."

And then...

Satyam pramdhithvyam!Dharmane pramdhithvyam!
Kushlaanpramdhithvyam!Bhoothyai na pramdithvyam!
Svadhyay pravachanbhyam na pramdhithvyam!

Meaning: Do not swerve from truth!Do not swerve from Dharma!
Work for the welfare of all! Take care of your self!
Share your knowledge with others!

And then the following sloka..

Devipitru karyabhayam na pramdhithvyam!
Mathudevo bhav! Pithudevo bhav!
Acharyadevo bhav!Aathidevo bhav!

Meaning:

Remember the Gods and your ancestors!
Honour your Mother.Look upon her as God!
Honour your father .Look upon him as God!
Honour your teacher as God!
Honour your guest.Look upon as if God came to receive your attention!
Then further...
"May you ever exercise your understanding and distinguish the good from the blame worthy,
Avoid the latter and ever do what is good,
Follow all that was good in your teacher's life, not any other.
You will meet better persons than even your teacher with whom you lived,to study,Show them due respect!"

And then the following sloka...

Shradya deyamAshardhya deyam!Shriya deyam!Hridya deyam!
Bhiya deyam!Sanvida deyam!

Meaning...

Give gifts with sincerity and not with indifference!
Give gifts with joy.Give gifts with humility!
Give gifts with fear lest they offend the recipient!Give gifts with kindness!

Further..

"If your mind is troubled with any doubt as to what is right or wrong ,follow the example of the gentle and the pious elders living in your neighbourhood,in regard to those matters."

And then concludes saying

"Yesh aadesh! Yesh upadesh!"

This is the rule ! This is the teaching!