Is expiation obligatory for someone who swore to his mother that he would die before her, and confirmed that with another oath, knowing that the time of death is in God's hands?

It is obligatory for a Muslim to revere the name of Allah and to reduce the frequency of taking oaths. An oath concerning a possible future event is a binding oath, and if one breaks it, expiation becomes necessary. The oath is broken if the mother dies before the one who swore the oath. According to jurists, a binding oath is one that relates to a possible future matter. It is neither a false oath (yamin ghamus) nor a vain oath (yamin laghw). This includes swearing about a possible future event and swearing about something that contradicts reality if the one swearing intended to do so.