עמוס ד:יג פירוש: רש״י

what his speech is—All his deeds are related in detail before him at the time of his death.

He makes dawn—for the righteous like a bright light.

darkness—He turns the brightness of the wicked into darkness. Cf. (Isa. 8:22) “And behold, distress and darkness, darkness (מְעוּף) of oppression.” Similarly, (Job 10:22) “Land of darkness (עֵפָתָה)”; (ibid. 11:17) “Darkness (תָּעֻפָה) shall be like morning.” Your darkness shall shine like the morning.