Is the forty-day mourning period for the deceased, and the word "mourning" (حداد), pre-Islamic (Jahiliyyah) or Christian?

The forty-day mourning period for the deceased is an innovation (bid'ah) and should be avoided. As for mourning for the deceased, it is prescribed for three days, and a wife may mourn for her husband for four months and ten days, based on the Almighty's saying: "And those of you who die and leave behind wives - they, [the wives], shall wait four months and ten [days]." And the Prophet, peace be upon him, said: "It is not permissible for a woman who believes in Allah and the Last Day to mourn for a deceased person for more than three nights, except for her husband, for four months and ten days."