Apannakasutta 4.2

4.2

Idha, bhikkhave, bhikkhu divasaṃ caṅkamena nisajjāya āvaraṇīyehi dhammehi cittaṃ parisodheti, rattiyā paṭhamaṃ yāmaṃ caṅkamena nisajjāya āvaraṇīyehi dhammehi cittaṃ parisodheti, rattiyā majjhimaṃ yāmaṃ dakkhiṇena passena sīhaseyyaṃ kappeti pāde pādaṃ accādhāya sato sampajāno uṭṭhānasaññaṃ manasi karitvā, rattiyā pacchimaṃ yāmaṃ paccuṭṭhāya caṅkamena nisajjāya āvaraṇīyehi dhammehi cittaṃ parisodheti.

It’s when a mendicant practices walking and sitting meditation by day, purifying their mind from obstacles. In the first watch of the night, they continue to practice walking and sitting meditation. In the middle watch, they lie down in the lion’s posture—on the right side, placing one foot on top of the other—mindful and aware, and focused on the time of getting up. In the last watch, they get up and continue to practice walking and sitting meditation, purifying their mind from obstacles.