Yōga Sūtra 3.32

कूर्मनाड्यां स्थैर्यम्।

kūrmanāḍyāṁ sthairyam।

[कूर्म नाड्यां स्थैर्यम्।
kūrma = on tortoise / base; nāḍyāṁ = channel; sthairyam = firmness;]

(by samyama) on the base channel one gains firmness.