What needs to be followed?

वाङ्मे मनसी प्रतिष्ठिता।
मनो मे वाचि प्रतिष्ठितम्।
आविराविर्मेधि वेदस्य माणिस्थः।

श्रुतं मे मा प्रहासीः। अनेनाधितेन।
अहोरात्रान्संदधामि। ऋतं वदिष्यामि।
सत्यं वदिष्यामि। तन्मामवतु।
तद्वक्तारमवतु। अवतु माम्।
अवतु वक्तारमवतु वक्तारम्॥ 

VaangmE manasee pratiShThitaa. manO mE vaachi pratiShThitam. aaviraavirmEdhi. vEdayamaaNisthaH. shrutam mE maa prahaaseeH. anEnaadhitEna. ahOraatraansaMdadhaami. Rutam vadiShyaami. Satyam vadishyaami. tanmaamavatu. tadvaktaaramavatu. avatu maam. avatu vaktaaram avatuvaktaaramavatu.

Shloka Translation:

What we talk, it should be thought thoroughly. The mind should be aligned when one talks.

The both are at peak when it is under the Vedic governance. When it is heard, one is joyously refreshed. This isn't just the beginning. I will preserve this even during night. I speak with enlightenment. I speak the truth. I am indulged into it. That is already mentioned as governance. I'll follow the same. The governance that governs.

This is the very first shloka of Aitthareeya Upanishat. The shloka is about what we talk and what we follow. Hence during the vedic period the disciple says that the governance is such that he/she abides by it and would follow the same always. And the assertion is that it is joyously refreshed when heard and that would lead to the enlightenment. Shri Shri Shankara Bhagavatpaada mentions the above shloka from Upanishat in his Brahmasutra bhashyas.