Dhammapada, Dhamma Verses (KN 2)

12: The Chapter about the Self – 72
Nagaraṁ yathā paccantaṁ guttaṁ santarabāhiraṁ,
As a border town is guarded on the inside and the outside,
evaṁ gopetha attānaṁ, khaṇo vo mā upaccagā,
so one should watch over oneself, and you should not let the moment pass,
khaṇātītā hi socanti nirayamhi samappitā. [315]
for when the chance has passed they grieve when consigned to the underworld.
Varam-assatarā dantā, ājānīyā ca Sindhavā,
Noble are the well-trained horses, the well-bred horses from Sindh,
kuñjarā ca mahānāgā, attadanto tato varaṁ. [322]
and the great tusker elephants, (and even) more noble than that is the one who has trained
himself.
Na hi etehi yānehi gaccheyya agataṁ disaṁ,
Not by these vehicles can one go to the place beyond destinations,
yathattanā sudantena, danto dantena gacchati. [323]
as one through training himself well, being trained by the training, goes.
Attanā codayattānaṁ, paṭimāsettam-attanā,
By oneself one should censure self, by oneself one should be controlled,
so attagutto satimā sukhaṁ bhikkhu vihāhisi. [379]
he who guards himself, mindful, will live happily, monastic.
Attā hi attano nātho, attā hi attano gati,
Self is the protector of self, self is the refuge of self,
tasmā saṁyamayattānaṁ assaṁ bhadraṁ va vāṇijo. [380]
therefore one should restrain oneself, as a merchant his noble horse.