You and other Bhikṣus, in day then, should be with the diligent mind practising good Dharma teachings, without leading to missed opportunities. In the first period of the night (i.e. 6 p.m. – 10 p.m.) and the later period of the night (i.e. 2 a.m. – 6 a.m.), also not having them abandoned. In the middle period of the night (i.e. 10 p.m. – 2 a.m.) reciting sūtras, with this naturally having restrained rest, not with drowsiness (i.e. also sleepiness) as cause and condition, that leads to this one life being passed in vain, without that attained. You should be mindful of the fire of impermanence, that burns all in the world, soon seek self-deliverance, and not [be] drowsy.
As all afflictions’ thieves, are constantly waiting to kill people, even more so than enemies, how can there be drowsiness, to not personally be vigilant to awaken? As afflictions’ poisonous snakes, sleeping in your minds, for example, are like black vipers, in your bedrooms sleeping, you should with the hook of upheld precepts, soon expel them. With the sleeping snakes already gone, then can there be peaceful sleep. With them not gone yet sleeping, is to be shameless persons.
The robes of [moral] shame (i.e. also humility), of all adornments, are as the most foremost. As shame is like an iron hook, able to restrain people from non-Dharma, therefore constantly should there be shame (i.e. also repentance), without having it temporarily replaced. If departing from shame, they will then lose all meritorious virtues. Of people having shame, they will then have good Dharma teachings. If there are those without shame, they are with all birds and beasts, without differences from one another.
The Sūtra Of The Buddha’s Bequeathed Teachings