You are reading a tafsir for the group of verses 28:81 to 28:82

According to the Bible, Moses cursed Korah for his evil deeds, and God caused him, his companions and his treasure to be swallowed up by the earth. This was visibly demonstrated by God as an example to clarify what the final result would be of leaving off the worship of God and adopting the worship of wealth. The amenities of the world are in fact given as a trial of human beings. These are provided to man, by the will of God in greater or lesser quantities. It is the duty of man to be patient if he receives fewer amenities and to be grateful if he receives more. This is the only way to the salvation and success of man.