There is a passage in Īśopaniṣad similar to a verse found in Śrīmad-Bhāgavatam (8.1.10) which states that whatever one sees in the cosmic manifestation is but the Supreme Lord's energy and is nondifferent from Him. Consequently He is the controller, friend and maintainer of all living entities. We should live by the mercy of God and take only those things which are allotted to us. In this way, by not encroaching on another's property, one can enjoy life.
In other words, the purpose of the Upaniṣads, Vedānta-sūtra and Śrīmad-Bhāgavatam is one and the same. If one studies Śrīmad-Bhāgavatam carefully, he will find that all the Upaniṣads and the Vedānta-sūtra are nicely explained therein. Śrīmad-Bhāgavatam teaches us how to reestablish our eternal relationship with the Supreme Lord, how to act in that relationship, and, lastly, how to achieve the highest benefit from it.