Bhagavad Gita 2.58

यदा संहारते चायं कूर्मोऽङ्गानीव सर्वशः |
इन्द्रियाणिन्द्रियार्थेभ्यस्तस्य प्रज्ञा प्रतिष्ठिता

Translation

One who is able to withdraw the senses from their objects, just as a tortoise withdraws its limbs into its shell, is established in divine wisdom.