Kaṭha Upaniṣad 3.5

3.5

yas tv avijñānavān bhavaty ayuktena manasā sadā /
tasyendriyāṇy avaśyāni duṣṭāśvā iva sāratheḥ //

7. He, however, who has not understanding,
Who is unmindful and ever impure,
Reaches not the goal,
But goes on to transmigration (saṃsāra).
8. He, however, who has understanding,
Who is mindful and ever pure,
Reaches the goal
From which he is born no more.
9. He, however, who has the understanding of a chariot-driver,
A man who reins in his mind—
He reaches the end of his journey,
That highest place of Vishṇu.