There is an isolated database table named "MESSAGE", with correspond class Message.

In a transaction, there exists a persistent Message object named "message".

Now,
session.delete(message);
// Now message is a transient object, isn't it?

Later, in the same transaction:

// Cancel the previous delete, so that object message
// becomes the original persistent object before the deletion.

// And then
message.setText("...");

// Finally,
tx.commit();
session.close();

How to do that
without an application-layer "deletetion-buffer", and
Hibernate generates only one "update" SQL statement ?

You may have considered this - but why not delay the deletion of the message until you know for sure that you are actually going to delete it?
i.e.