Money given via cash and returned via RTGS

I gave 4 lacs to my relative after withdrawing from my bank , he returned same amount via RTGS after 8 months in my account. Now relation got strained between us and he has filed recovery suit on me stating that he has given loan of 4 lacs to me via RTGS , but I am not returning him the amount. I have few questions in this situation : 1. Since plaintiff is only having RTGS to support his claim of Loan , he is not carrying any other evidences to prove his claim of loan. In this situation , can he transfer burden of proof on defendant(myself) only on the basis of RTGS ? 2. Since RTGS is only mode of Payment is RTGS sufficient to transfer burden on proof or any other evidences are required in court to prove recovery suit. Can recovery done only on basis of RTGS ? 3. Do I need to prove in court with the help of additional witnesses that I gave him 4 Lacs in cash which he later returned? or I can go in court and simply say I have given him cash 4 lacs after withdwawing from bank and prove bank account statement by summoning bank ? Do additional witnesses are required in this case from my side.