Bank postings can me made as on current date or 5 days back before that system would not allow

Hi Experts,

My client would like to make the bank related postings as on the current date or 5 days before the current date before this system would not allow the user to make the postings. I am trying the same with the validation however not been able to input the 5 days logic into the validation point.

Regards

Abhisekh Mandal