B.G 2.58
यदा संहरते चायं कूर्मोङ्गानीव सर्वशः। इंद्रियाणींद्रियार्थेभ्यस्तस्य प्रज्ञा प्रतिष्ठिता ॥५८॥
yadā saṃharate cāyaṃ kūrmo'ṅgānīva sarvaśaḥ। indriyāṇīndriyārthebhyas tasya prajñā pratiṣṭhitā ॥58॥
[यदा (yadā) - when; संहरते (saṃharate) - withdraws; च (ca) - and; अयम् (ayam) - this; कूर्मः (kūrmaḥ) - tortoise; अङ्गानि (aṅgāni) - limbs; इव (iva) - like; सर्वशः (sarvaśaḥ) - altogether; इन्द्रियाणि (indriyāṇi) - the senses; इन्द्रियार्थेभ्यः (indriyārthebhyaḥ) - from the sense objects; तस्य (tasya) - his; प्रज्ञा (prajñā) - wisdom; प्रतिष्ठिता (pratiṣṭhitā) - is established;]
(When a person withdraws his senses from the sense objects on all sides, just as a tortoise withdraws its limbs, then his wisdom is firmly established.)
When he withdraws his senses all together from the objects of senses, like the limbs of a tortoise, his wisdom is well established.