I have:
INSERT INTO post(title,message) VALUES (:title,:message)
where :message value has some random text with symbols (including comma).
As the comma symbol is the separator between components of the statement:
How can i escape :message value to keep its included commas in the string context and not be interpreted as the separator?
You don’t need to. The whole point of using prepared statements, as you are with PDO, is that the structure of the query is sent separately from the data. This means that characters in the data are never confused for parts of the structure of the query.
You’ve done all you need to do to make the query safe in this regard.