Sayyiduna Jabir (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him) said: "No illness is contagious from one person to another, there is no bad omen in anything, and there are no such things as ghouls." (By ghouls is meant the common belief that there are devils in the wilderness who shine like lamps at night, sometimes guiding people and sometimes killing them.)