"There is a youth leader in the Congress who has just learnt to speak. I am glad that he (Gandhi) has started to speak now.
"In 2009, it was very difficult to find out what was inside this packet. Good he has started speaking. And there was no possibility of any earthquake.
"Had he not spoken, the county would have faced a big earthquake. And the country could not have recovered for 10 years," Modi said sarcastically at an event at the Banaras Hindu University (BHU) in Varanasi, his Lok Sabha constituency.
Gandhi had threatened to make damning disclosures against Modi. On Wednesday, he said in Gujarat that Income Tax documents showed Modi had taken kickbacks from corporate houses when he was the Chief Minister.
Modi is on a day-long trip to Varanasi where he is to lay foundation stones of several projects and address Bharatiya Janata Party activists.
Modi did not spare former Prime Minister Manmohan Singh and former Finance Minister P. Chidambaram either. Like Gandhi, both have denounced the demonetisation of high value currency.
Modi said he never thought that a few political leaders and political parties would stand with the corrupt when the government tried to clean up black money through the note ban.
About Manmohan Singh, Modi said: "When I spoke about cashless economy, he said how can this technology function where 50 per cent people are poor.
"Now, tell me whether he is giving his own report card or mine? Whose legacy am I bearing now?"
In similar vein, Modi attacked Chidambaram: "He said in a country where there is no electricity in 50 per cent of the villages, how can you implement cashless economy.
"I want to ask if he is talking about his report card or mine?"