In the Scrum Guide, under the Increment portion of the Scrum Artifacts section, it says:
At the end of a Sprint, the new Increment must be "Done," which means it must be in useable condition and meet the Scrum Team’s definition of "Done".
Supporting that statement, under the Definition of "Done" section, it says:
This is the definition of "Done" for the Scrum Team and is used to assess when work is complete on the product Increment.