You are reading a tafsir for the group of verses 29:38 to 29:40
وَعَادًا
وَّثَمُوْدَاۡ
وَقَدْ
تَّبَیَّنَ
لَكُمْ
مِّنْ
مَّسٰكِنِهِمْ ۫
وَزَیَّنَ
لَهُمُ
الشَّیْطٰنُ
اَعْمَالَهُمْ
فَصَدَّهُمْ
عَنِ
السَّبِیْلِ
وَكَانُوْا
مُسْتَبْصِرِیْنَ
۟ۙ
وَقَارُوْنَ
وَفِرْعَوْنَ
وَهَامٰنَ ۫
وَلَقَدْ
جَآءَهُمْ
مُّوْسٰی
بِالْبَیِّنٰتِ
فَاسْتَكْبَرُوْا
فِی
الْاَرْضِ
وَمَا
كَانُوْا
سٰبِقِیْنَ
۟ۚۖ
فَكُلًّا
اَخَذْنَا
بِذَنْۢبِهٖ ۚ
فَمِنْهُمْ
مَّنْ
اَرْسَلْنَا
عَلَیْهِ
حَاصِبًا ۚ
وَمِنْهُمْ
مَّنْ
اَخَذَتْهُ
الصَّیْحَةُ ۚ
وَمِنْهُمْ
مَّنْ
خَسَفْنَا
بِهِ
الْاَرْضَ ۚ
وَمِنْهُمْ
مَّنْ
اَغْرَقْنَا ۚ
وَمَا
كَانَ
اللّٰهُ
لِیَظْلِمَهُمْ
وَلٰكِنْ
كَانُوْۤا
اَنْفُسَهُمْ
یَظْلِمُوْنَ
۟
3

Commentary

The stories of the earlier people, that are mentioned in these verses briefly, have been related in detail in the previous Surahs. For instance, the story of Shu'aib and those of ` Ad and Thamud have been related in Surahs Al-A` raf and Hud, and the incidents of Qarun, Haman, and the Pharaoh have just passed in Surah Al- Qasas.

وَكَانُوا مُسْتَبْصِرِ‌ينَ (They were people of insight - 29:38). This word is derived from Istibsar, which means sight; and Mustabsir is used for observer. The meaning of this sentence is that those who insisted on infidelity and shirk (associating partner with Allah) and got themselves involved in perdition and Allah's wrath were no fools or insane. They were very clever having insight, but their intelligence and sagacity was confined to mundane considerations. They did not realize that there would be a day of reckoning for all good and bad actions, when there would be complete justice, because the cruel and the oppressors move about in this world without hindrance, but those oppressed and afflicted are compelled to endure injustice. The day this injustice will finish and justice will be the order of the day is called the Hereafter. They are at a loss to comprehend this bit.

The same subject is coming ahead in Surah Ar-Rum, where it is said يَعْلَمُونَ ظَاهِرً‌ا مِّنَ الْحَيَاةِ الدُّنْيَا وَهُمْ عَنِ الْآخِرَ‌ةِ هُمْ غَافِلُونَ (They know what is superficial of the worldly life, but of the Hereafter they are negligent. - 30:7). .

Some commentators have interpreted the meaning of وَكَانُوا مُسْتَبْصِرِ‌ينَ (They were people of insight) that these people did have faith in their heart and did understand well the necessity of the Day of Judgment, but the mundane considerations had compelled them to reject it.