It does not hurt in SEO, because there are many of situation when people link to your sources and forgot to mention
/ slash at the end of URL, www and https, so your server may already redirect them by default, like this
http://www.example.com/source redirect to www.example.com/source/
http://example.com/source/ redirect to https://example.com/source/
example.com/source/ will redirect to www.example.com/source/
While may be in future, your source file is deleted by you, so all user and cralwer/spider will first see 301 redirection then 404 error, so it is common in many situation, hence I said it does not hurt in SEO.
But as stephen said, don't link your article in this way, example.com/abc because Google may not reach to your proper page. So make sure your all example.com/en/abc link to example.com/en/source only.
Use Google fetch and render tool to see how Google view your redirection.