The Qur’an says...
The Qur’an says: “Verily Korah was of the people of Moses, but he oppressed them…” The cause of this oppression and disobedience was that he had obtained a great deal of wealth, and since he had not enough capacity and strong faith, this abundant wealth deceived him and drew him towards deviation and arrogance.
The Qur’an continues saying: “…and We had given him of the treasures so much that its keys would have been a burden to a company of men endowed with strength…” The Arabic word /mafatih/ is the plural form of /maftah/ in the sense of ‘a place wherein something is stored’, like the chests that properties are stored up in them. Thus, the concept of the verse is that Korah had so much gold, silver and precious properties that a group of strong men could move its box with difficulty.
And, regarding that the Arabic word /‘usbah/ means a body of men (from ten to forty) who are with together and are strong enough and they have held each other like nerves, makes it clear that how heavy the jewels and precious properties of Korah had been. The term /tanu’/ is derived from /nu’/ which means: to raise with difficulty and heavily, and it is used for a heavy burden that when a man is carrying it, because of heaviness, it causes him to sway this side and that side.
What was said in the above about the Arabic term /mafatih/ is something that a very large group of commentators and lexicologists have accepted, while some other commentators have said that the term /mafatih/ is the plural form of /miftah/ which means key. They say that the keys of the treasures of Korah were so heavy that several strong men could carry them with difficulty.
Those who have chosen this meaning have got in trouble to themselves to adjust it that how it is possible to be so many keys of treasures, and, however, the first commentary is more clear and more correct. Now, it is better to see what the Children of Israel told Korah. The Holy Qur’an implicitly says: remember when his people told him not to have so much joy flourished with pride, negligence and arrogance, because Allah does not like the proud exultant.