Is a man's saying, "May everything be cursed," when angry, considered an act of disbelief (kufr), knowing that he did not intend anything forbidden?

The aforementioned phrase is offensive and should be avoided. As for declaring its utterer an apostate, that is a possibility, as it might be a curse for something that necessitates disbelief or for worldly matters. Since the phrase can imply disbelief or other meanings, a Muslim should not be declared an apostate because of it unless the meaning of disbelief is intended with certainty, because the fundamental principle is that a Muslim remains in their Islam. If ninety-nine interpretations point to declaring a Muslim an apostate, and one interpretation points to keeping them in their Islam, then the latter interpretation should be acted upon.