From an Agile view-point, the business requirements to the developers should be expressed as single sentences. These single sentence functional requirements are called user stories.
The Sprint Backlog for any given Sprint should list the user stories (by their IDs) that are planned to be developed during that Sprint.
Each and every user story is an invitation for the developer to talk with the Business User about the details of that specific requirement.
In my personal experience, the best expression of the business requirement they could come up with is a group of unit tests that describe the requirement in a “good enough” fashion.
As the team should be using “Test First Development”, all they should work on is just enough code to have all the unit tests for that requirement, which at that moment, these tests should not pass.
This should not take much time to accomplish, so the Business User will be free to talk to some other developer about some other user story, while the developer could start working on adding just enough code to have all the tests in “green”.