Chāndogya Upaniṣad 4.17.10

4.17.10

mānavaḥ \
brahmaivaika ṛtvik (S ) \
evaṃvid dha vai brahmā yajñaṃ yajamānaṃ sarvāṃś cartvijo 'bhirakṣati \
tasmād evaṃvidam eva brahmāṇaṃ kurvīta nānevaṃvidaṃ nānevaṃvidam \\417.10\

Verily, the Brahman priest who knows this guards the sacrifice, the institutor of the sacrifice, and all the priests. Therefore one should make as his Brahman priest one who knows this, not one who does not know this—yea, not one who does not know this.

9. Verily, that sacrifice is inclined to the north in which there is a Brahman priest who knows this. Verily, there is this song on the Brahman priest who knows this:— Whichever way he turns himself, In that same way goes common man. The Brahman priest alone protects The sacrificers like a dog.