Ihdad (mourning) may only be three days but for a husband-that is, if the husband dies-then the longer of the ihdad is four months and ten days. Rasulullah shallallohu 'alaihi wasallam said,
"It is not lawful for a woman who believes in Allah and the Last Day berihdad (joined) over the dead more than three nights except for the husband that is four months and ten days