Once, King Prasenajit of Kosala came to visit Buddha and paid his respects. After sitting down, he asked Buddha, "World Honored One, when I am meditating alone, I often have this thought in my mind: 'Who has protected themselves? Who has not?'"

Buddha replied, "Your Majesty, here is my answer to your question: Anyone who engages in evil deeds with their body and speech or harbors evil thoughts within themselves cannot be said to have protected themselves. Even if they are surrounded by armies of elephants, cavalrymen, chariots or infantrymen for protection from external threats; since their internal selves are not being safeguarded properly from within by good deeds and thoughts; they cannot be considered as having truly protected themselves."

"Conversely," continued Buddha," anyone who engages in good deeds with their body and speech or harbors good thoughts within themselves can be said to have already protected themselves. Even if they do not have any external protection such as armies of elephants or soldiers guarding them; because their internal selves are being safeguarded properly from within by good deeds and thoughts; they can still be considered as having truly protected themselves."

King Prasenajit agreed with Buddha's explanation.

Buddha further explained that those who engage in good behavior will naturally refrain from doing evil things even when faced with difficult situations. They possess a sense of shame which guides them towards what is right and wrong. These individuals frequently engage in virtuous actions through their bodies and words while cultivating positive thoughts internally. They never commit even the slightest wrongdoing.

Therefore it can be concluded that only those individuals who protect their inner selves through virtuous conduct are the ones who truly protect themselves."

At this moment, the Buddha recited a verse:

"Good indeed is self-control of the body,

Good indeed is self-control of speech.

Good indeed is self-control of thought,

So truly, well-controlled are all things.

One who controls oneself out of a sense of shame

Is truly worthy to be called a guard of humanity."

Pali original scripture

SN.3.5/(5) Attarakkhitasuttaṃ

　　 116. Sāvatthinidānaṃ. Ekamantaṃ nisinno kho rājā pasenadi kosalo bhagavantaṃ etadavoca– “idha mayhaṃ, bhante, rahogatassa paṭisallīnassa evaṃ cetaso parivitakko udapādi– ‘kesaṃ nu kho rakkhito attā, kesaṃ arakkhito attā’ti? Tassa mayhaṃ, bhante, etadahosi– ‘ye kho keci kāyena duccaritaṃ caranti, vācāya duccaritaṃ caranti, manasā duccaritaṃ caranti; tesaṃ arakkhito attā. Kiñcāpi te hatthikāyo vā rakkheyya, assakāyo vā rakkheyya, rathakāyo vā rakkheyya, pattikāyo vā rakkheyya; atha kho tesaṃ arakkhito attā. Taṃ kissa hetu? Bāhirā hesā rakkhā, nesā rakkhā ajjhattikā; tasmā tesaṃ arakkhito attā. Ye ca kho keci kāyena sucaritaṃ caranti, vācāya sucaritaṃ caranti, manasā sucaritaṃ caranti; tesaṃ rakkhito attā. Kiñcāpi te neva hatthikāyo rakkheyya, na assakāyo rakkheyya, na rathakāyo rakkheyya na pattikāyo rakkheyya; atha kho tesaṃ rakkhito attā. Taṃ kissa hetu? Ajjhattikā hesā rakkhā, nesā rakkhā bāhirā; tasmā tesaṃ rakkhito attā’”ti.

　　 “Evametaṃ, mahārāja, evametaṃ, mahārāja! Ye hi keci, mahārāja, kāyena duccaritaṃ caranti …pe… tesaṃ arakkhito attā. Taṃ kissa hetu? Bāhirā hesā, mahārāja, rakkhā, nesā rakkhā ajjhattikā; tasmā tesaṃ arakkhito attā. Ye ca kho keci, mahārāja, kāyena sucaritaṃ caranti, vācāya sucaritaṃ caranti, manasā sucaritaṃ caranti; tesaṃ rakkhito attā. Kiñcāpi te neva hatthikāyo rakkheyya, na assakāyo rakkheyya, na rathakāyo rakkheyya, na pattikāyo rakkheyya; atha kho tesaṃ rakkhito attā. Taṃ kissa hetu? Ajjhattikā hesā, mahārāja, rakkhā, nesā rakkhā bāhirā; tasmā tesaṃ rakkhito attā”ti. Idamavoca …pe…

　　 “Kāyena saṃvaro sādhu, sādhu vācāya saṃvaro;

　　 Manasā saṃvaro sādhu, sādhu sabbattha saṃvaro.

　　 Sabbattha saṃvuto lajjī, rakkhitoti pavuccatī”ti.