Bhagavad Gita · 12.10

अभ्यासेऽप्यसमर्थोऽसि मत्कर्मपरमो भव।मदर्थमपि कर्माणि कुर्वन्सिद्धिमवाप्स्यसि॥

abhyāse 'py asamartho 'si mat-karma-paramo bhava mad-artham api karmāṇi kurvan siddhim avāpsyasi

If you are unable even to practice regularly, then devote yourself to performing actions for my sake. Even by performing actions for me, you shall attain perfection.

— Bhagavad Gita 12.10

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