“Do not lay up for yourselves treasures on earth, where moth and rust destroy and where thieves break in and steal, but lay up for yourselves treasures in heaven, where neither moth nor rust destroys and where thieves do not break in and steal. For where your treasure is, there your heart will be also. The eye is the lamp of the body. So, if your eye is healthy, your whole body will be full of light, but if your eye is bad, your whole body will be full of darkness. If then the light in you is darkness, how great is the darkness! “No one can serve two masters, for either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve God and money. Mathew 6:19-24 (ESV)
Here the Bible clearly says that we must not store up earthly treasures for ourselves, What are earthly treasures? Well it's things like money and possessions. We need to store up treasures in heaven. Our heart shows us where our treasures truly are.
As for the rich in this present age, charge them not to be haughty, nor to set their hopes on the uncertainty of riches, but on God, who richly provides us with everything to enjoy. They are to do good, to be rich in good works, to be generous and ready to share, thus storing up treasure for themselves as a good foundation for the future, so that they may take hold of that which is truly life. 1 Timothy 6:17-19 (ESV)
We need to keep our spiritual eyes fixed on God not on earthly things that will make us full of darkness. We can't serve God and earthly things at the same time we are either serving one or the other.
You adulterous people! Do you not know that friendship with the world is enmity with God? Therefore whoever wishes to be a friend of the world makes himself an enemy of God James 4:4 (ESV)