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Surah 28. Al-Qasas
Ayah 81 - 82
٨١. فَخَسَفْنَا بِهِۦ وَبِدَارِهِ ٱلْأَرْضَ فَمَا كَانَ لَهُۥ مِن فِئَةٍ يَنصُرُونَهُۥ مِن دُونِ ٱللَّهِ وَمَا كَانَ مِنَ ٱلْمُنتَصِرِينَ
٨٢. وَأَصْبَحَ ٱلَّذِينَ تَمَنَّوْا۟ مَكَانَهُۥ بِٱلْأَمْسِ يَقُولُونَ وَيْكَأَنَّ ٱللَّهَ يَبْسُطُ ٱلرِّزْقَ لِمَن يَشَآءُ مِنْ عِبَادِهِۦ وَيَقْدِرُ ۖ لَوْلَآ أَن مَّنَّ ٱللَّهُ عَلَيْنَا لَخَسَفَ بِنَا ۖ وَيْكَأَنَّهُۥ لَا يُفْلِحُ ٱلْكَـٰفِرُونَ
[81-82] Consequently, We sank him and his people in all his dwelling place underground; then he had no host of supporters, who could help him against Allah, nor was he able to help himself. Now the same people who yearned for his lot the day before, began to say, "Alas! We had forgotten that Allah extends the provisions for whom He wills of His servants and restricts it for whom He wills.101 If Allah had not been gracious to us, He would have sunk us also underground. Alas! We did not remember that the disbelievers do never prosper."102
101That is "The extension or the restriction of provisions is always according to the will of Allah, and Allah's will is determined by His own reasons and considerations. His favoring somebody with generous provisions does not necessarily mean that Allah is well pleased with him and is honoring him with gifts. Mostly it so happens that a person is under Allah's wrath, but He goes on favoring him with wore and more wealth till, at last, the same wealth causes Allah's torment to descend on him. Contrary to this, if somebody is being given restricted provisions it does not necessarily mean that Allah is displeased with him and is punishing him. Mostly the righteous then live in hardship although they are Allah's favorites, and in many cases the same hardship becomes a cause of Allah's mercy for them. Consequently, a person who does not understand this reality looks with envious eyes at the prosperity of those who actually deserve Allah's wrath."
102That is, "We had the misconception, that worldly prosperity and wealth by themselves constituted real success. Therefore, we thought that Korah was highly .successful, but now we have come to know that real success is an entirely different thing, and it is never attained by the disbelievers."
This moral of the story of Korah has been mentioned only in the Qur'an. The Bible and the Talmud are without it. However, according to the details given in these books, when the Israelites left Egypt, Korah also accompanied theta along with his men, and then conspired against the Prophets Moses and Aaron and was joined in this by 250 of his followers. At last, Allah's wrath descended on him, and the earth opened up and swallowed him and his followers together with their possessions."