Once, vibhishana was imprisoned by some brahmanas. When Sri Rama-chandra, the gem of  Raghu dynasty, heard that his great devotee was in distress, he became much worried. He sent his messengers in all directions in search of Vibhishana. Finally, the whereabouts of Vibhishana were found. Sri Ramachandra himself went to meet Vibhishana.
And what a sight he saw! The brahmanas had tied Vibhishana’s hands and legs and imprisoned him in a cellar. Sri Ramachandra was shocked at this plight of this great devotee with good qualities. He enquired the brahmanas about Vibhishana’s crime. Upon seeing Sri Ramachandra, the brahmanas prostrated at his feet and welcomed him with great honour. Then, they said to him: ‘O Lord! One day, an asura came to the forest near our ashrama in a chariot. An old brahmana of the ashrama had gone to the forest to collect durvagrass.
The asura asked him something. The old brahmana could not reply as he was keeping a vow of silence. Angered at this, the asura kicked the old brahmana, who fell down, and died on the spot. On learning this, we went and imprisoned that asura. No matter how much we beat him, he did not die. Your arrival here is a great blessing to us. You have to punish this murderous sinner.’
The brahmanas pleaded to Sri Ramachandra. They brought the bound Vibhishana in front of Sri Ramachandra. Vibhishana was greatly embarrassed to see Sri Ramachandra. Sri Ramachandra became uncomfortable seeing Vibhishana’s condition. Sri Ramachandra said to the brahmanas: ‘The master alone is responsible for any fault of his servants. Therefore, please release Vibhishana.
I bless him that he live till the end of this kalpa and order him to rule Lanka. He is mine. Hence, any fault of his is as good as my fault and please give me the punishment that you had intended for him. I am bound to accept it without any complaint. ’Vibhishana did not intentionally kill the brahmana, who was old and keeping a vow of silence, which Vibhishana did not know. So, the brahmanas desired Vibhishana’s atonement for a crime done unknowingly. However, Vibhishana did not have to atone; Sri Ramachandra did that for his devotee