Must a son carry out his father's will to marry a girl whom the son deems unsuitable for him and who is twenty years his junior?

Summary:

The Prophet, peace and blessings be upon him, advised marrying a religious woman. If the girl your father recommended is religious, then marrying her is an act of compliance with the Prophet's command and your father's recommendation. The age difference does not affect marital happiness, as Umar ibn al-Khattab married Umm Kulthum bint Ali, may Allah be pleased with them both, and he was approximately forty years older than her. However, if she is not religious and righteous, then the command of the Messenger of Allah, peace and blessings be upon him, is more deserving of being followed.