[c#] How can I implement static methods on an interface?

I have a 3rd party C++ DLL that I call from C#.

The methods are static.

I want to abstract it out to do some unit testing so I created an interface with the static methods in it but now my program errors with:

The modifier 'static' is not valid for this item

MyMethod cannot be accessed with an instance reference; qualify it with a type name instead

How can I achieve this abstraction?

My code looks like this

private IInterfaceWithStaticMethods MyInterface;

public MyClass(IInterfaceWithStaticMethods myInterface)
{
  this.MyInterface = myInterface;
}

public void MyMethod()
{
  MyInterface.StaticMethod();
}