Union Minister Ravi Shankar Prasad on Friday said Congress Vice President Rahul Gandhi needs to learn and understand demonetisation before saying anything on the subject."Demonetisation is the biggest campaign against corrupt people and black money. The poor would benefit the most and Rahul Ganndhi should not say anything without thinking about it," Prasad said in his reply to Rahul Gandhi's opposition to demonetisation.Prasad said Rahul Gandhi is yet to study and learn a lot before opposing demonetisation.But Prasad refused to say anything on Rahul Gandhi's corruption allegations against Prime Minister Narendra Modi.Rahul Gandhi has alleged that Modi had taken money from corporate houses when he was Gujarat Chief Minister