Bhagavad Gita · Chapter 9: The Royal Knowledge and Royal Secret

Bhagavad Gita 9.21

te taṃ bhuktvā svargalokaṃ viśālaṃ kṣīṇe puṇye martyalokaṃ viśanti | evaṃ trayīdharmamanuprapannā gatāgataṃ kāmakāmā labhante ||

Having enjoyed that vast heavenly world, they return to the world of mortals when their merit is used up. So those who follow the rites of the three Vedas, wanting pleasures, gain only coming and going.

Modern context

Heaven is like a bank account. When the merit is spent, one returns. The verse names the result plainly: 'coming and going'. A life aimed at rewards, however high, keeps a person in a cycle of earning and spending. This is true in ordinary life too. Working only for the next reward means always needing the next one. Freedom lies in aiming at something that is not used up.