diff --git a/config/default.yml b/config/default.yml
index 066980353a..6150915d27 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -960,6 +960,7 @@ Rails/ToSWithArgument:
 
 Rails/TopLevelHashWithIndifferentAccess:
   Description: 'Identifies top-level `HashWithIndifferentAccess`.'
+  Reference: 'https://guides.rubyonrails.org/upgrading_ruby_on_rails.html#top-level-hashwithindifferentaccess-is-soft-deprecated'
   Enabled: pending
   VersionAdded: '<<next>>'