﴿ وَقَضَيْنَآ إِلَيْهِ ذَٰلِكَ ٱلْأَمْرَ أَنَّ دَابِرَ هَٰٓؤُلَآءِ مَقْطُوعٌۭ مُّصْبِحِينَ ﴾

“And [through Our messengers] We revealed unto him this decree: "The last remnant of those [sinners] shall be wiped out" in the morn."”

And We conveyed We revealed to him the matter which was that these sinners was to be eradicated by morning musbihīn is a circumstantial qualifier in other words their annihilation will take place in the morning.