Asking for Cash payment by builder in plot buying...

Hello sir, We have bought 1.plot(1500sf) in Indore, MP. (Gov.rate is Rs. 558/sf And market rate is 1251 Rs.), Registry done 2 weeks before on Gov. Rate. And according to Gov.rate/registry rate we have paid Rs. 8,37,000/- by cheque to builder. Now the remaining amount Rs. 11,90,900/-* he is asking for cash. * [(1251×1500)18,76,500+60,000(electricity)+20,000(maintenance)+71,400(registry)=20,27,900-8,37,000 = 11,90,900/- And for this we have taken Home Loan of 12LACS, so out of 8,37,000 bank given cheque of 5,37,000 to builder and remaining amount 3lacs we have given to builder by cheque. Now registry has done on my name on 25th July 2016, after this I dont know what documents given to Bank by the builder and registrar office, builder given us one photocopy of allotment letter mentioning the plot details, amount Rs.8,37,000/- Now I have received the remaining amount of Rs. 6,54,875/- in my acount as Loan amount from the ibulls bank, and builder is asking this money in Cash, not by cheque. So should we give in cash ??? He is saying that registry amount 837000 done by cheque so remaining amount by cash will be no problm for you. What consequence might be of this ??? We did not get any registry receipt also as the amount paid by the Builder that time, this receipt will be deposited with bank or builder should give us after clearing all payments?? Thank you, A. Karma