Srimad Bhagavatam Canto 10, Chapter 24, Text 13

SB 10.24.13

sri-bhagavan uvaca
karmana jayate jantuh
 karmanaiva praliyate
sukham duhkham bhayam ksemam
Lord Krsna said: It is by the force of karma that a living entity takes birth, and it is by karma alone that he meets his destruction. His happiness, distress, fear and sense of security all arise as the effects of karma.
Lord Krsna minimized the importance of the demigods by speaking the philosophy known as Karma-vada or Karma-mimamsa, which, basically, is atheism with a belief in reincarnation. According to this philosophy, there are subtle laws of nature that reward or punish us according to how we act: “As you sow, so shall you reap.” In a future life one reaps the fruit of his present work, and this is the sum and substance of reality. Lord Krsna, being God Himself, could hardly be a serious proponent of this mediocre philosophy. In the role of a young boy He was simply teasing His pure devotees by preaching it.
Srila Jiva Gosvami points out that Lord Krsna was thinking, “Why are these eternal associates of Mine, appearing as My father and other relatives and friends, so caught up in this worship of Indra?” Thus although the Lord’s main purpose was to take away the false pride of Indra, He also wanted to remind His eternal devotees that they need not divert their attention to other so-called gods, since in fact His devotees were already living with the Supreme Absolute Truth, the almighty Lord Himself.
Srimad Bhagavatam Canto 10, Chapter 24, Text 12
Srimad Bhagavatam Canto 10, Chapter 24, Text 14