Bhagavad Gita · 11.54

भक्त्या त्वनन्यया शक्य अहमेवंविधोऽर्जुन।ज्ञातुं द्रष्टुं च तत्त्वेन प्रवेष्टुं च परन्तप॥

bhaktyā tv ananyayā śhakya aham evaṁ-vidho 'rjuna jñātuṁ draṣhṭuṁ cha tattvena praveṣhṭuṁ cha parantapa

But through exclusive, undivided devotion alone, O Arjuna, I can be known, truly seen, and entered into, O scorcher of foes.

— Bhagavad Gita 11.54

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)