Musannaf Ibn Abi Shayba 18:402

Abu Bakr narrated to us, he said: Ad-Dahhak bin Makhlad narrated to us, from Ibn Jurayj, from Ibn Abi Najih, from Mujahid regarding the nail: If it does not grow back, then in it is a bint makhad (a one-year-old female camel). If it is not found, then in it is a bint labun (a two-year-old female camel).