Bhagavad Gita · 12.9

अथ चित्तं समाधातुं न शक्नोषि मयि स्थिरम्।अभ्यासयोगेन ततो मामिच्छाप्तुं धनञ्जय॥

atha chittaṁ samādhātuṁ na śhaknoṣhi mayi sthiram abhyāsa-yogena tato mām ichchhāptuṁ dhanañjaya

If you are unable to fix your mind steadily on me, then seek to reach me through the yoga of repeated practice, O Arjuna.

— Bhagavad Gita 12.9

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