E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cut neither Nails nor Hair at Sea.
Petronius says, Non licere ouiquam mortalium in nave neque ungues neque capillos deponere, nisi cum pelago ventus irascitur. The cuttings of the nails and hair were votive offerings to Proserpine, and it would excite the jealousy of Neptune to make offerings to another in his own special kingdom.