Whenever you're dealing with a message in your template, you're actually working with a MessageModel object.
Outputting a MessageModel object without attaching a property or method will return the message's content.
<p>{{ message }}</p>
Returns a UserModel object representing the message's author.
The message's author ID.
The message's content.
A DateTime object of the date the message was created.
A DateTime object of the date the message was last updated.
The message's ID.
The message's ticket ID.