In the Puranas, there is a famous story, a development of a story from the Kenopanishad. The Gods, Indra, Agni, Varuna and Vayu (the lords of heaven, fire, water and air) were elated over their past victory over the Asuras (demons), and vainly attributed it to themselves. Sri Krishna, intending to cure them of their blind vanity, approached them, as they were boasting to one another that there was nothing they could not do.
He asked Agni, “What can you do?”
Agni replied, “I can burn up everything in the univese”.
Krishna placed a piece of dried-up darbha grass before him and said, “Burn it”.
Agni tried his best but could not burn it.
Krishna asked Varuna, “What can you do?”
“I can drown or dissolve or wash away everything in the world,” said he.
“All right. Dissolve this,” said Krishna, and placed some ashes before him.
Varuna tried his best, but could not drown or dissolve or wash away the sacred ashes.
Krishna asked Vayu, “What can you do?”
“I can carry away for miles, anything I like,” said Vayu.
“All right. Carry away this piece of cotton used for making holy threads,” said Krishna.
Vayu tried his best, but could not move it by a hair’s breadth.
Krishna asked Indra, “What can you do?”
“I can destroy anything with my thunder-bolt,” said Indra.
“Destroy this agnihotram mud pot”, said Krishna placing the pot before him.
Indra tried his best, but failed.
Then Uma, the great consort of Siva and the sister of Krishna, went there, and said to Indra, Varuna, Agni and Vayu, “The terrible Asura, Hiranyakasipu, must be fought and destroyed. Whoever is Supreme among you gods, come at once and rescue the world!”
Indra said at once, in terror: “I am not the Supreme”. Varuna followed, and said, “Nor I”. Agni chimed in “Nor I”. Vayu added “Nor I”.
Then Uma pointed to Krishna, and said, “He is the Supreme. Let Him fight the demon”. And Krishna agreed and incarnated Himself, as Narasimha, Man-Lion, from a fraction of Himself, and destroyed Hiranya, in spite of all the boons so carefully secured by that demon.