Bhagavad Gita · 5.6

सन्न्यासस्तु महाबाहो दुःखमाप्तुमयोगतः।योगयुक्तो मुनिर्ब्रह्म नचिरेणाधिगच्छति॥

sannyāsas tu mahā-bāho duḥkham āptum ayogataḥ yoga-yukto munir brahma na chireṇādhigachchhati

But renunciation of action, O mighty-armed one, is difficult to attain without the practice of selfless action. A sage who is disciplined in the yoga of action attains Brahman without delay.

— Bhagavad Gita 5.6

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