Hathayoga 1-34

Śavaâsana

उत्तानं शबवद्भूमौ शयनं तच्छवासनम् ।

शवासनं श्रान्ति-हरं चित्त-विश्रान्ति-कारकम् ॥ ३४॥

Uttānam śabavadbhūmau śayanam tachchavāsanam Śavāsanam śrāntiharam chittaviśrāntikārakam

Lying down on the ground, like a corpse, is called Śavaâsana. It removes fatigue and gives rest to the mind.