Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the polytheists used to part their hair, and the People of the Book used to leave their hair without parting it. Until a new and specific command was given to the Noble Prophet (peace and blessings be upon him), he preferred to conform to the People of the Book. Therefore, in the beginning, he (peace and blessings be upon him) used to leave his hair on his forehead, then he started parting his hair.