According to Bṛhaddevatā, Indra, immediately on his birth, fought with Sage Vāmadeva for 10 days and nights.
What is the mystery behind Sage Vāmadeva fighting with Indra?
There is a refrence in Mahabharat where Indra tried to kill Vamadeva in war.
The Stories or Myths that were indicated in the Bṛhaddevatā, like fight of Vāmadeva with Indra, do not find place in Rig Veda.
However, these stories are in the form of an explanation to Rig Vedic mantras, which were composed in a cryptic manner, unintelligible to a person with less inclination towards SPIRITUALITY.
The fight between Vāmadeva and Indra should be understood in a SPIRITUAL line only.
Actually there was no fight between Vāmadeva and Indra.
It was Vāmadeva , who had been in SELF REALISATION stage even in his mother's womb! It must be Indra's defeating the EGO of Vāmadeva.
And, Gautama placing (selling) him in the assembly of seers, indicates Indra presenting in the assembly of seers, as Gautama himself is Indra, as Vāmadeva became a REALISED one and thus had become Indra himself.
Vāmadeva's hymn must be based on his own experience.