For self-protection one should practise amity for the vier royal families of snakes:
Virūpakkha
Erāpatha
Chabyāputta
Kashā-gotamaka
It was preached when ein Mönch was bitten by a snake at Sāvatthi. A.ii.72. Vergl. Vin.ii.109; SA.ii.144.
Another name for it is the Khandhaka Paritta.