Date validation :before -1 day

I really liked the tool but I have got stuck in one case. I am in urgent
need of your help regarding

validates_date :sale_start, :before => :sale_end,
                  :after => { }

validates_date :sale_end, :after => [:sale_start ,
                               { }],

This is Okay but there may be the same date as of sale_end. Means a sale
can be for a single day, in that case sale_start and sale_end both
fields may have the same date but this syntax or :after property does
not allow me to do so. It accepts only one day after the sale_start
date. So will you please suggest me how can I set it as the same day.

Your help will be appreciated.