Strange Anomoly with New Posts

This is very strange.

I wrote this post, here: https://www.ilmfruits.com/good-character/

Originally, the first line had the word selected–so it read:

“The following ahadeeth are selected from Ibn Hajr …”

Now, if what I quoted above (minus the …) is ALL that’s in the post, I can’t save or publish or edit the post–I see a 404 on post.php. However, if I remove the word “from”, or change it to “fraa” or some other thing like that, everything works fine…

It’s very bizzare..this even happens if all my plugins are disabled.

Thankfully, I just deleted the word selected, and it worked … but what’s going on here?