सर्वद्वाराणि संयम्य मनो हृदि निरुध्य च। मूर्ध्न्याधायात्मनः प्राणमास्थितो योगधारणाम्।।8.12।।
sarva-dvārāṇi sanyamya mano hṛidi nirudhya cha mūrdhnyādhāyātmanaḥ prāṇam āsthito yoga-dhāraṇām
Having closed all the gates, confined the mind in the heart, and fixed the life-breath in the head, engage in the practice of concentration.