"So when they forgot that which they were reminded of," meaning: they abandoned that which they were exhorted with.
"We seized them with a wretched punishment," meaning: severe. "[They became] apes, disgraced," meaning: cast away.
Qatada said: They became apes, howling, possessing tails.
Qatada said: It reached us that someone entered upon Ibn Abbas while the Mushaf was before him, and he was weeping, having reached this verse: "So when they forgot that which they were reminded of." He said: I know that God destroyed those who took the fish, and saved those who forbade them, but I do not know what He did with those who neither forbade [the sin] nor committed the transgression.
al-Hasan said: And what prohibition could be more severe than the fact that they confirmed the threat for them and frightened them with the punishment? For they said: "Why do you preach to a people whom God is about to destroy or punish with a severe punishment?"
﴿فَلَمَّا نَسُوا مَا ذُكِّرُوا بِهِ﴾ أَيْ: تَرَكُوا مَا وُعِظُوا بِهِ.
﴿أَخَذْنَاهُم بعذابٍ بئيس﴾ أَي: شَدِيد ﴿قردة خَاسِئِينَ﴾ أَيْ مُبْعَدِينَ.
قَالَ قَتَادَةُ: فَصَارُوا قردةً تعاوى لَهَا أَذْنَابٌ.
قَالَ قَتَادَةُ: وَبَلَغَنَا أَنَّهُ دُخِلَ عَلَى ابْنِ عَبَّاسٍ، وَبَيْنَ يَدَيْهِ الْمُصْحَفُ، وَهُوَ يَبْكِي وَقَدْ أَتَى عَلَى هَذِهِ الآيَةِ: ﴿فَلَمَّا نَسُوا مَا ذُكِّرُوا بِهِ﴾ فَقَالَ: قَدْ عَلِمْتُ أَنَّ اللَّهَ أَهْلَكَ الَّذِينَ أَخَذُوا الْحِيتَانَ، وَنَجَّى الَّذين نهوهم، وَلَا أَدْرِي مَا صَنَعَ بِالَّذِينَ لَمْ يَنْهَوْا وَلَمْ يُوَاقِعُوا الْمَعْصِيَةَ.
قَالَ الْحَسَنُ: وَأَيُّ نَهِيٍّ يَكُونُ أَشَدَّ مِنْ أَنَّهُمْ أَثْبَتُوا لَهُمُ الْوَعِيدَ، وَخَوَّفُوهُمُ الْعَذَابَ، فَقَالُوا: ﴿لِمَ تَعِظُونَ قَوْمًا اللَّهُ مُهْلِكُهُمْ أَوْ مُعَذِّبُهُمْ عذَابا شَدِيدا﴾.
