Hanuman’s tail is set on fire in Lanka but Hanuman feels no pain – this wonderful incident is mentioned in the Sundhara Kanda of Ramayana. Hanuman who allowed himself to be captured by Indrajit is taken to the court of Ravana. Here Hanuman tries to reason with Ravana regarding the release of Mata Sita.
Demon King Ravana does not listen to Hanuman but decides to kill Him. Vibhishana, brother of Ravana, argues that it is not as per Dharma to harm a messenger. Finally, Ravana decides to punish Hanuman by setting His tail on fire.
Rakshasis rushed to Sita to inform her about the decision of Ravana.
Mata Sita is horrified at the fate of Hanuman. She then invokes Agni, the god of fire. Sita says that if it is true that she has served her husband as her only lord, if it is true that she has observed all vrats and performed tapas with pure mind, then Hanuman should not feel the heat of fire.
Agni then blesses Hanuman.
Hanuman whose tail was set on fire too was amused that even though it was burning bright he did not feel the heat. He felt coolness as though sandal paste has been applied to his tail.
Hanuman uses the fire on his tail to set Lanka on fire.