Surah 28. Al-Qasas, Ayah 76

The structure of the above sentence is meant to show that even a person who had been a follower of one of the greatest of God's apostles was not above the possibility of sinning under the influence of false pride and self-exaltation - a particular example of the "false imagery" referred to in the preceding passage. The conventional "identification" of Qarun with the Korah of the Old Testament (Numbers xvi) is neither relevant nor warranted by the Qur'anic text, the more so as the purport of this legend is a moral lesson and not a historical narrative. this, by the way, explains also the juxtaposition, elsewhere in the Qur'an ( 29:39 and 40:24 ), of Qarun with Pharoah, the arch-sinner.

The term 'usbah denotes a company of ten or more (up to forty) persons; since it is used here metonymically, pointing to the great weight involved, it is best rendered as above. - The noun mafatih is a plural of both miftah or miftah ("key") and muftah ("that which is under lock and key", i.e., a "hoard of wealth" or "treasure chest"), which latter meaning is obviously the one intended in the present context.

 Korah was the cousin of Moses. Because of Korah’s close association with Pharaoh, he became very rich and started to behave arrogantly towards his own people. When he was asked repeatedly by Moses (ﷺ) to pay his alms-tax to help poor Israelites, Korah refused and eventually conspired with a prostitute to damage the reputation of Moses, but Moses was cleared of any wrongdoing.

Qarun is identified with the Korah of the English Bible. His story is told in Num. xvi. 1-35. He and his followers, numbering 250 men, rose in rebellion against Moses and Aaron, on the ground that their position and fame in the congregation entitled them to quality in spiritual matters with the Priests,-that they were as holy as any, and they claimed to burn incense at the sacred Altar reserved for the Priests. They had an exemplary punishment: "the earth opened her mouth, and swallowed them up, and their houses, and all the men that appertained unto Korah, and all their goods: they, and all that appertained to them, went down alive into the pit, and the earth closed upon them: and they perished from among the congregation."

Qarun's boundless wealth is described in the Midrashim, or the Jewish compilations based on the oral teachings of the Synagogues, which however exaggerate the weight of the keys to be the equivalent of the load of 300 mules!

Usbat: a body of men, here used indefinitely. It usually implies a body of 10 to 40 men. The old-fashioned keys were big and heavy, and if there were hundreds of treasure-chests, the keys must have been a great weight. As they were travelling in the desert, the treasures were presumably left behind in Egypt, and only the keys were carried. The disloyal Qarun had left his heart in Egypt, with his treasures.