diff --git a/pydantic/validators.py b/pydantic/validators.py
--- a/pydantic/validators.py
+++ b/pydantic/validators.py
@@ -568,9 +568,7 @@ def find_validators(  # noqa: C901 (ignore complexity)
     if config.arbitrary_types_allowed:
         yield make_arbitrary_type_validator(type_)
     else:
-        raise RuntimeError(
-            f'no validator found for {type_} see `keep_untouched` or `arbitrary_types_allowed` in Config'
-        )
+        raise RuntimeError(f'no validator found for {type_}, see `arbitrary_types_allowed` in Config')
 
 
 def _find_supertype(type_: AnyType) -> Optional[AnyType]:

I agree the name isn't that clear, but I think it's too late to change.

Happy to accept a PR to update the documentation, or even update the error message if we can do it asap.
diff --git a/tests/test_main.py b/tests/test_main.py
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -951,7 +951,7 @@ def class_name(cls) -> str:
 
     assert str(e.value) == (
         "no validator found for <class 'tests.test_main.test_custom_types_fail_without_keep_untouched.<locals>."
-        "_ClassPropertyDescriptor'> see `keep_untouched` or `arbitrary_types_allowed` in Config"
+        "_ClassPropertyDescriptor'>, see `arbitrary_types_allowed` in Config"
     )
 
     class Model(BaseModel):

Behaviour of keep_untouched is unclear in docs
# Bug

* Python version `import sys; print(sys.version)`: 3.7.3
* Pydantic version `import pydantic; print(pydantic.VERSION)`: 0.32.2

The `keep_untouched` attribute on a model's Config affects the behaviour for properties' **values**, not their **type annotations**. This is unclear, and is also made particularly misleading by the wording of [this error message](https://github.com/samuelcolvin/pydantic/blob/master/pydantic/validators.py#L572):
```
RuntimeError: no validator found for {type_} see `keep_untouched` or `arbitrary_types_allowed` in Config
```
These should both be improved, and perhaps the config attribute's name should also be changed?

tests/test_main.py::test_custom_types_fail_without_keep_untouched
tests/test_main.py::test_success tests/test_main.py::test_ultra_simple_missing tests/test_main.py::test_ultra_simple_failed tests/test_main.py::test_comparing tests/test_main.py::test_nullable_strings_success tests/test_main.py::test_nullable_strings_fails tests/test_main.py::test_recursion tests/test_main.py::test_recursion_fails tests/test_main.py::test_not_required tests/test_main.py::test_infer_type tests/test_main.py::test_allow_extra tests/test_main.py::test_forbidden_extra_success tests/test_main.py::test_forbidden_extra_fails tests/test_main.py::test_disallow_mutation tests/test_main.py::test_extra_allowed tests/test_main.py::test_extra_ignored tests/test_main.py::test_set_attr tests/test_main.py::test_set_attr_invalid tests/test_main.py::test_any tests/test_main.py::test_alias tests/test_main.py::test_population_by_field_name tests/test_main.py::test_field_order tests/test_main.py::test_required tests/test_main.py::test_not_immutability tests/test_main.py::test_immutability tests/test_main.py::test_const_validates tests/test_main.py::test_const_uses_default tests/test_main.py::test_const_with_wrong_value tests/test_main.py::test_const_list tests/test_main.py::test_const_list_with_wrong_value tests/test_main.py::test_const_validation_json_serializable tests/test_main.py::test_validating_assignment_pass tests/test_main.py::test_validating_assignment_fail tests/test_main.py::test_enum_values tests/test_main.py::test_enum_raw tests/test_main.py::test_set_tuple_values tests/test_main.py::test_default_copy tests/test_main.py::test_arbitrary_type_allowed_validation_success tests/test_main.py::test_arbitrary_type_allowed_validation_fails tests/test_main.py::test_arbitrary_types_not_allowed tests/test_main.py::test_type_type_validation_success tests/test_main.py::test_type_type_subclass_validation_success tests/test_main.py::test_type_type_validation_fails_for_instance tests/test_main.py::test_type_type_validation_fails_for_basic_type tests/test_main.py::test_annotation_field_name_shadows_attribute tests/test_main.py::test_value_field_name_shadows_attribute tests/test_main.py::test_class_var tests/test_main.py::test_fields_set tests/test_main.py::test_skip_defaults_dict tests/test_main.py::test_skip_defaults_recursive tests/test_main.py::test_dict_skip_defaults_populated_by_alias tests/test_main.py::test_dict_skip_defaults_populated_by_alias_with_extra tests/test_main.py::test_dir_fields tests/test_main.py::test_dict_with_extra_keys tests/test_main.py::test_alias_generator tests/test_main.py::test_alias_generator_with_field_schema tests/test_main.py::test_alias_generator_wrong_type_error tests/test_main.py::test_root tests/test_main.py::test_root_list tests/test_main.py::test_root_failed tests/test_main.py::test_root_undefined_failed tests/test_main.py::test_parse_root_as_mapping tests/test_main.py::test_untouched_types tests/test_main.py::test_model_iteration tests/test_main.py::test_custom_init_subclass_params