فَبِأَىِّ حَدِيثٍ بَعْدَهُ يُؤْمِنُونَ

(In what message after this will they then believe) Allah says, what more warnings, and discouragements should compel them to believe, if the warnings and threats that Muhammad ﷺ brought them from Allah in His Book do not compel them to do so Allah said next,