Rails 3.2 Dynamic belongs to based off two separate columns

I have a model called TimesheetCorrection which has date column, a user_id column, hours column.

There is also a timesheet model which has the same columns. What I want to do is do a belongs_to :timesheet on the TimesheetCorrection model based on

WHERE timesheets.user_id = timesheet_corrections.user_id AND timesheets.date = timesheet_corrections.date

What would the syntax be to achieve that with active record?