The matter was listed for hearing before Metropolitan Magistrate Gomati Manocha, who allowed the pleas filed by lawyers representing both the leaders seeking exemption from personal appearance for the day.
Earlier, Singh had contended before the court that Gadkari has not placed any "admissible evidence" against him in the defamation complaint.
Gadkari's lawyer had countered Singh's submissions saying admissibility of evidence could be seen at the stage of trial.
Singh, who was summoned as an accused in the matter, had said that "in my life I have never withdrawn my statement".
The defamation complaint was filed by Gadkari in 2012 against Singh, who was earlier granted bail by the court which, after finding "prima facie" evidence against him, had directed the Congress leader to appear before it as accused for offence punishable under sections 499 (defamation) and 500 (punishment for defamation) of IPC.