Delhi Chief Minister Arvind Kejriwal on Thursday took on Prime Minister Narendra Modi after former aide Rajendra Kumar, seeking retirement from government service, alleged that the CBI was pressurising him to implicate the Aam Aadmi Party (AAP) leader."CBI raids my office, pressurises officer to implicate me. CBI raids Satinder Jain's office. Why are you so so scared of us Modiji? Chill!" Kejriwal tweeted, referring to CBI's December raid on Delhi Health Minister Satyendar Jain's OSD Nikunj Aggarwal's office and Kumar's allegations.IAS officer Rajendra Kumar, Kejriwal's former Principal Secretary, earlier said he has tendered voluntary retirement request claiming officials at the Central Bureau of Investigation were pressurising him to name the "Chief Minister".