Can anyone tell me what episode this image is from?(from tumblr)(not mine)

It's from "The End", it is the moment when Dean and Future!Dean were pulled aside to chat about the truth and the fact Future!Dean is using his team as bait. He ends up knocking out the Past Dean.

i think it might be from "the end" (season 5) after samifer (lucifer in sam's body) killed 2014 dean.

Why don't you ask the person who posted it on Tumblr.

I am probably wrong, but my first thought looking at this was that it's a spoiler picture for season 8. I really not sure sorry :)