Bhagavad Gita · 4.39

श्रद्धावाँल्लभते ज्ञानं तत्परः संयतेन्द्रियः।ज्ञानं लब्ध्वा परां शान्तिमचिरेणाधिगच्छति॥

śhraddhāvān labhate jñānaṁ tat-paraḥ saṁyatendriyaḥ jñānaṁ labdhvā parāṁ śhāntim achireṇādhigachchhati

The faithful one, devoted to that knowledge, with senses controlled, attains knowledge; and having attained knowledge, one quickly reaches supreme peace.

— Bhagavad Gita 4.39

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