For self-protection one should practise amity for the four royal families of snakes:
Virúpakkha
Erápatha
Chabyáputta
Kashá-gotamaka
It was preached when a monk was bitten by a snake at Sávatthi. A.ii.72. Cp. Vin.ii.109; SA.ii.144.
Another name for it is the Khandhaka Paritta.