“In the long run, no one can retain what does not belong to him by right of consciousness, nor be deprived of that which is truly his by the same supreme title.
Therefore, you will do well not to lay up treasures upon the earth, but rather to lay up treasure in heaven; that is, the understanding of Spiritual Law. If you are looking to outer, passing, mutable things for either happiness or security, you are not putting God first. If you are putting God first in your life, you will not find yourself laboring under undue anxiety about anything, for where your treasure is, there will your heart be also.
Treasure in Heaven" from "The Sermon on the Mount" Emmet Fox
It is always dangerous to cherry-pick a phrase out of the context it is in. Here is one case especially if you have never studied Emmet Fox's writings. Reading the preceding 4 paragraphs in "Treasure in Heaven" is essential to get an understanding of what he is saying here. Most adults taught that you should do good works without getting compensation. That God would pay you when you die and go to heaven. With this logic, if you love what you do to earn a living you will never get to heaven.
Here are the three preceding paragraphs to give you some insight to his meaning.
The safest banks can and do fail; unforeseen catastrophes happen on the stock market; mines and oil wells five out or may be destroyed by some natural cataclysm; a new invention may easily ruin an old one, the opening or closing of a railroad station, or the starting of some new enterprise somewhere else, may ruin the value of your real estate, to say nothing of the unpredictable effect of unexpected political upheavals upon every kind of property. In short, it is a waste of time to give too much attention to collecting material possessions which are so vulnerable to changes and chances, to "moth and rust," and thieves.
If a reasonable part of the time and attention that most people spend in the pursuit of material goods were devoted by them to scientific prayer and meditation, the change in consciousness which would follow would put them beyond any possibility of suffering from any of these hazards.
If you had sufficient spiritual understanding of supply, your investments probably would not go wrong: but if they did, your posses would e immediately replaced in some other way, and before you had time to suffer from them. If let us say, the bank in which your fortune was deposited should stop payment on Monday, then, probably before the end of the week, an equivalent sum of money, or at least as much as you could possibly need, would come to you from somewhere else - if you had sufficient spiritual understanding. If any case, the owner of a prosperity consciousness cannot be impoverished; nor, for the matter of that, can the owner of a poverty consciousness be permanently enriched.