Original: The very earliest accounts are contained in these texts, such as early Christian creeds and hymns, as well as accounts of the Passion, the empty tomb, and Resurrection appearances; often these are dated to within a decade or so of the crucifixion of Jesus, originating within the Jerusalem Church.
Simplified: The very earliest reports are in these texts: early Christian creeds and hymns and reports about the Passion, the empty tomb, and appearances of Jesus after his Resurrection.