The story of Shambuka is told in the seventh book, Uttarakanda, of the Valmiki Ramayana. Shambuka wants to achieve a higher status than the suras (devtas, gods) through meditation and austerities. On discovering that Shambuka, a Shudra, was indeed meditating, Rama promptly beheads him to restore varnasharma dharma. The story has been used by the Dravidian movement and in anticaste literature to ridicule the idea of Rama as the embodiment of perfection.

Ambedkar, B R, Annihilation of Caste_ The …, loc. 1121