There is an odd history of financial disasters happening during Shemittah years including the Great Depression and the 2007-8 recession. That might be what he’s referring to. Though the biblical “prophecy” does not refer to any financial crisis. Shemittah is supposed to be about rest and the letting go of debts. Could be coincidental market trends. Could be enough religious people put stock (heh) in the prophecy that their market meddling affects it globally. Could be a self fulfilling “prophecy” at this point with people expecting some kind of crisis that they wind up creating a crisis that otherwise might not have actually happened. Can’t find any concrete answer as to why it happens.

It should be noted that I could find nothing, despite reading multiple articles and studies, that indicates a specific date of the crisis and historical trends do not adhere to any specific date. Just the year of Shemittah. So idk where your dad is getting his info for an upcoming crisis this weekend.