Translator's note: This is one of the few protective charms mentioned in the Pali canon and specifically allowed by the Buddha for monks to use (another charm, also allowed to the monks, is contained in DN 32 ). Note that the power of the charm is said to come, not from the words, but from the mind of good will with which they are said. It thus differs from charms taught in later forms of Buddhism, where the words themselves are said to contain power.

On one occasion the Blessed One was staying near Savatthi in Jeta's Grove, Anathapindika 's monastery. Now, at that time in Savatthi a certain monk had died after having been bitten by a snake. Then a large number of monks went to the Blessed One and, on arrival, having bowed down to him, sat to one side. As they were sitting there they said to him, "Lord, just now in Savatthi a certain monk died after having been bitten by a snake."

"Then it's certain, monks, that that monk didn't suffuse the four royal snake lineages with a mind of good will. For if he had suffused the four royal snake lineages with a mind of good will, he would not have died after having been bitten by a snake. Which four? The Virupakkha royal snake lineage, [1] the Erapatha royal snake lineage, the Chabyaputta royal snake lineage, the Dark Gotamaka royal snake lineage. It's certain that that monk didn't suffuse these four royal snake lineages with a mind of good will. For if he had suffused these four royal snake lineages with a mind of good will, he would not have died after having been bitten by a snake. I allow you, monks, to suffuse these four royal snake lineages with a mind of good will for the sake of self-protection, self-guarding, self-preservation."

I have good will for the Virupakkhas, good will for the Erapathas, good will for the Chabyaputtas, good will for the Dark Gotamakas. I have good will for footless beings, good will for two-footed beings, good will for four-footed beings, good will for many-footed beings. May footless beings do me no harm. May two-footed beings do me no harm. May four-footed beings do me no harm. May many-footed beings do me no harm. May all creatures, all breathing things, all beings — each & every one — meet with good fortune. May none of them come to any evil. Limitless is the Buddha, limitless the Dhamma, limitless the Sangha. There is a limit to creeping things: snakes, scorpions, centipedes, spiders, lizards, & rats. I have made this safeguard, I have made this protection. May the beings depart. I pay homage to the Blessed One, homage to the seven rightly self-awakened ones. [2]

Notes

1 .: The Virupakkhas are the chiefs of the nagas, associated with the western quarter (see DN 20 ). The other royal lineages of snakes are nowhere else mentioned in the Pali canon. The commentary to this discourse does not identify them.
2 .: The seven most recent Buddhas, including "our" Buddha, are mentioned in DN 14 & DN 32 : Vipassi, Sikhi, Vessabhu, Kakusandha, Konagamana, Kassapa, and Gotama. It's noteworthy that the concept of the seven Buddhas is associated with protective charms. For example, the heart of the charm given in DN 32 is this:
Homage to Vipassi, possessed of vision & splendor. Homage to Sikhi, sympathetic to all beings. Homage to Vessabhu, cleansed, austere. Homage to Kakusandha, crusher of Mara's host. Homage to Konagamana, the Brahman who lived the life perfected. Homage to Kassapa, entirely released. Homage to Angirasa [Gotama], splendid son of the Sakyans, who taught this Dhamma: the dispelling of all stress & pain. Those unbound in the world, who have seen things as they are, great ones of gentle speech, thoroughly mature, even they pay homage to Gotama, the benefit of human & heavenly beings, consummate in knowledge & conduct, the great one, thoroughly mature. We revere the Buddha Gotama, consummate in knowledge & conduct.