Is it permissible for me to swear a false oath to please my mother, who refuses my marriage to a girl of good character, and what is the expiation if I do so out of necessity?

Lying is forbidden, and swearing falsely upon it is a more severe prohibition. It is not permissible to swear falsely except to achieve a legitimate Shar'i objective that cannot be achieved except through it, such as someone who is compelled to marry and fears falling into forbidden things if he does not marry, and his mother insists that he swear. However, it is possible to dispense with lying by using ta’riyah (equivocation) and ambiguities, which is employing general terms from which the listener understands something other than what the speaker intends. 'Umar said: "Are there not in ambiguities what suffice the Muslim from lying?" You can swear to your mother that you did not speak to her, intending: that you did not speak to her today or yesterday. A Muslim should not put others in a situation where they are forced to lie.