"And indeed, those before them denied"—before your people, O Muhammad—"and how [great] was My disapproval?" as an interrogative; meaning: it was severe; and "My disapproval" means: My punishment.
Muhammad said: Ibn Mujahid mentioned that Warsh narrated from Nafi': "My warner" and "My disapproval" with a ya' during connection. He said: And the rest recited with a kasra on the ra' without a ya' in either connection or pause. Interpretation of Surah al-Mulk from verses (19-25).
﴿وَلَقَدْ كَذَّبَ الَّذِينَ مِنْ قَبْلِهِمْ﴾ قَبْلَ قَوْمِكَ يَا مُحَمَّدُ ﴿فَكَيْفَ كَانَ نَكِير﴾ عَلَى الِاسْتِفْهَامِ؛ أَيْ: كَانَ شَدِيدًا؛ وَنَكِيرِي: عُقُوبَتِي.
قَالَ مُحَمَّدٌ: ذَكَرَ ابْنُ مُجَاهِدٍ (٢) أَنَّ وَرْشًا رَوَى عَنْ نَافِعٍ: ﴿نَذِيرِي﴾ وَ ﴿نَكِيرِي﴾ بياء فِي الْوَصْلِ. قَالَ: وَقَرَأَ الْبَاقُونَ بِكَسْرِ الرَّاءِ مِنْ غَيْرِ يَاءٍ فِي وصل وَلَا وقف (٣). تَفْسِير سُورَة الْملك من آيَة (١٩ - ٢٥)