Musannaf Ibn Abi Shayba 18:401

Abu Bakr narrated to us, he said: Ad-Dahhak bin Makhlad narrated to us, from Ibn Jurayj, regarding the fingernail: If it does not grow back, then in it are two she-camels. If it grows back blind, having no luster (or shine), then in it is one she-camel.