ChU 6.12.3
स य एषो ऽणिमैतद् आत्म्यम् इदं सर्वम् । तत् सत्यम् । स आत्मा । तत् त्वम् असि श्वेतकेतो इति । भूय एव मा भगवान् विज्ञापयत्व् इति । तथा सोम्येति होवाच
sa ya eṣo 'ṇimaitad ātmyam idaṃ sarvam | tat satyam | sa ātmā | tat tvam asi śvetaketo iti | bhūya eva mā bhagavān vijñāpayatv iti | tathā somyeti hovāca
Devanagari rendered by HREEM from the edition's roman (IAST) text; the IAST is the edition's own.
'Believe it, my son. That which is the subtile essence, in it all that exists has its self. It is the True. It is the Self, and thou, O Svetaketu, art it.' 'Please, Sir, inform me still more,' said the son. 'Be it so, my child,' the father replied.
Translated by F. Max Müller