You can see the source, even if you don't have edit privileges. If you click edit you will see the actual source of the post. Make sure not to submit the edit unless you really want to.
Another option is to check the revision history. It has an option source.
The URL of the revision history is
POSTID is the ID of the question or answer you can find it in the URL or using the Share button). In the case of your question it is https://meta.stackexchange.com/posts/257778/revisions. Its source can be found here.
If a question or answer is edited, you can also click the edited XXX ago link next to the post flair.