«وَسَلَّتِ الصُّبْحُ خِضَابَهُ»
And dawn drew away the night's dye.
Sallat expresses drawing or pulling something out; khiḍāb is a colouring substance or dye. Dawn becomes an active force removing the dark colouring of the night.
Night taking off its covering and morning drawing away its dye are two images of the same transition. Both personify time, turning night and day into acting characters.