"And there certainly seized them early in the morning a stable punishment," meaning the punishment settled upon them.
Muhammad said: "Bukratan" (early in the morning) is indefinite here. If you were referring to the morning of your specific day, you would make it diptote (ghayr munsarif), and likewise with "ghudwatan" (early morning) in a similar context.
Tafsir of Surat al-Qamar from verse 41 to verse 48.
﴿وَلَقَدْ صَبَّحَهُمْ بُكْرَةً عَذَابٌ مُسْتَقِرٌّ﴾ استقرَّ بهم الْعَذَاب.
قَالَ محمدٌ: (بكرَة) هَا هُنَا نكرَة، وَإِذا أردْت بكرَة يَوْمك لم تَصْرِفْها وَكَذَلِكَ (غدْوَة) فِي مثل هَذَا.
تَفْسِير سُورَة الْقَمَر من الْآيَة ٤١ إِلَى الْآيَة ٤٨.
