Sutta Pitaka Vol 4 : Sutta. Ma. Mū. Mahāassapurasuttaṃ:
What more is there to do?
You should train yourselves like this: ‘We will be committed to
wakefulness.
- When practicing walking and sitting meditation by day, we will
purifying our mind from obstacles.
- In the evening, we will continue to practice walking and sitting
meditation.
- In the middle of the night, we will 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 part of the night, we will get up and continue to
practice walking and sitting meditation, purifying our mind from
obstacles.’
Now, mendicants, you might think: ‘We have conscience and prudence,
our bodily, verbal, and mental behavior is pure, our livelihood is
pure, our sense doors are restrained, we don’t eat too much, and we
are committed to wakefulness. Just this much is enough …’