diff --git a/en/appendices/5-3-migration-guide.rst b/en/appendices/5-3-migration-guide.rst
index 85978e974e..f06cff05aa 100644
--- a/en/appendices/5-3-migration-guide.rst
+++ b/en/appendices/5-3-migration-guide.rst
@@ -22,6 +22,12 @@ Database
 - ``Query::with()`` now accepts an array of expressions to align with other query clauses. This also
    allows clearing the expressions with an empty array.
 
+Validation
+----------
+
+- The signature of ``Validator::validate(array $data, bool $newRecord = true, array $context = [])`` has now a additional third parameter ``$context``.
+  It can be used to pass necessary context into the validation when marshalling.
+
 View
 ----
 
@@ -106,6 +112,8 @@ Validation
 ----------
 
 - ``ipOrRange()`` validation has has been added to check for an IP or a range (subnet).
+- When validating within CakePHP marshalling context, the entity will be passed into the ``context`` argument for use inside custom validation rules.
+  This can be useful when patching partially and then needing to get that data from the entity instead of the passed data.
 
 TestSuite
 ---------
diff --git a/en/core-libraries/validation.rst b/en/core-libraries/validation.rst
index 4e4b37ddca..f7c14db6d0 100644
--- a/en/core-libraries/validation.rst
+++ b/en/core-libraries/validation.rst
@@ -195,12 +195,17 @@ containing data related to the validation process:
   need to create complex rules by calling multiple providers.
 - **newRecord**: Whether the validation call is for a new record or
   a preexisting one.
+- **entity**: The entity being validated if provided to ``validate()``.
 
 Closures should return boolean true if the validation passes. If it fails,
 return boolean false or for a custom error message return a string, see the
 :ref:`Conditional/Dynamic Error Messages <dynamic_validation_error_messages>`
 section for further details.
 
+.. versionchanged:: 5.3.0
+   The ``entity`` key was added to validation context.
+
+
 .. _dynamic_validation_error_messages:
 
 Conditional/Dynamic Error Messages