येनाश्रुतं श्रुतं भवति
The Shruti statement is mentioned in Chandogya Upanishad 6.1.3
When Shvetaketu (श्वेतकेतु) is returned after studying Vedas for 12 years, his father Uddalaka Aruni (उद्दालक आरुणि) asked him “Did you learned that knowledge, after learning which the unknown become known ?”
In this statement Aruni was explaining the importance of the Self Knowledge (आत्मज्ञान), which when known explain everything in this creation.
येनाश्रुतं श्रुतं भवति – Complete Shruti
येनाश्रुतं श्रुतं भवत्यमतं मतमविज्ञातं विज्ञातमिति
English Meaning
(Self-Knowledge) By leaning which unheard become heard, the unthought become thought, the unknown become known.