Introduction
In many later tellings of the Ramayana, the rumour that led Rama to send Sita away is given a face: an unnamed washerman (dhobi) of Ayodhya. In Valmiki's Uttara Kanda, Rama learns of the rumours from his companion Bhadra, and no washerman is mentioned.
This article follows later traditions, where the washerman appears.
The story in later tellings
In these versions, Rama disguised himself and walked through the city at night. He overheard a washerman quarrelling with his wife, who had stayed away from home for a night. The washerman said he was not like Rama, who had taken back a wife who had lived in another man's house. Rama took this as a sign of what his subjects thought, and sent Sita into exile.
A later addition
This story is not in Valmiki. It appears in later Sanskrit and regional works, and is one of the most well-known parts of the Ramayana tradition.