Mundaka 6.04

नायमात्मा बलहीनेन लभ्यो न च प्रमादात् तपसो वाऽप्यलिङ्गात्। एतैरुपायैर्यतते यस्तु विद्वां स्तस्यैष आत्मा विशते ब्रह्मधाम ॥४॥

nāyamātmā balahīnena labhyo na ca pramādāt tapaso vā'pyaliṅgāt। etairupāyairyatate yastu vidvāṁ stasyaiṣa ātmā viśate brahmadhāma ॥4॥

[न (na) - not; अयम् (ayam) - this; आत्मा (ātmā) - Ātmān; बलहीनेन (balahīnena) - by the weak; लभ्यः (labhyaḥ) - attainable; न (na) - not; च (ca) - and; प्रमादात् (pramādāt) - by heedlessness; तपसः (tapasaḥ) - by austerity; वा (vā) - or; अपि (api) - even; अलिङ्गात् (aliṅgāt) - without proper conduct; एतैः (etaiḥ) - by these; उपायैः (upāyaiḥ) - means; यतते (yatate) - strives; यः (yaḥ) - who; तु (tu) - indeed; विद्वान् (vidvān) - wise; तस्य (tasya) - his; एषः (eṣaḥ) - this; आत्मा (ātmā) - self; विशते (viśate) - enters; ब्रह्मधाम (brahmadhāma) - the abode of Brahman;]

The Ātmān cannot be attained by the weak, nor by heedlessness, nor even by austerity without proper conduct. However, the self of the wise who strives by these means indeed enters the abode of Brahman.