“‘Come, mendicant, be committed to wakefulness. Practice walking and sitting meditation by day, purifying your mind from obstacles. In the first watch of the night, continue to practice walking and sitting meditation. In the middle watch, 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, get up and continue to practice walking and sitting meditation, purifying your mind from obstacles.’ ”