keystone/api-ref/source/v3/samples/admin/auth-password-unscoped-request.json

{
    "auth": {
        "identity": {
            "methods": [
                "password"
            ],
            "password": {
                "user": {
                    "id": "423f19a4ac1e4f48bbb4180756e6eb6c",
                    "password": "devstacker"
                }
            }
        }
    }
}