BṚHADĀRAṆYAKA UPANISHAD · 1.4.8

तद् एतत् प्रेयः पुत्रात् प्रेयो वित्तात् प्रेयो ऽन्यस्मात् सर्वस्माद् अन्तरतरं यद् अयम् आत्मा ।
स यो ऽन्यम् आत्मनः प्रियं ब्रुवाणं ब्रूयात् प्रियं रोत्स्यतीतीश्वरो ह तथैव स्यात् ।
आत्मानम् एव प्रियम् उपासीत ।
स य आत्मानम् एव प्रियम् उपास्ते न हास्य प्रियं प्रमायुकं भवति ॥

tad etat preyaḥ putrāt preyo vittāt preyo ’nyasmāt sarvasmād antarataraṃ yad ayam ātmā ।
sa yo ’nyam ātmanaḥ priyaṃ bruvāṇaṃ brūyāt priyaṃ rotsyatītīśvaro ha tathaiva syāt ।
ātmānam eva priyam upāsīta ।
sa ya ātmānam eva priyam upāste na hāsya priyaṃ pramāyukaṃ bhavati ॥

This, which is nearer to us than anything, this Self, is dearer than a son, dearer than wealth, dearer than all else. And if one were to say to one who declares another than the Self dear, that he will lose what is dear to him, very likely it would be so. Let him worship the Self alone as dear. He who worships the Self alone as dear, the object of his love will never perish.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)