This is from an old fanfiction called "A precious Rainbow"
It was a Wubcake reading video, but ever since her channel was deleted, (I think) that video along with this picture were completely lost. I genuinely tried looking for it all over the internet, I searched it top-to-bottom, I visited the wayback machine, and some weird sites aswell...
But I found nothing.
Then one day, some random guy from the pony archive just posted it on youtube. The creator of this picture was wubcake herself, she merely edited a screencap to keep the viewer's attention going throughout the video.
And if she's here and she wants me to delete it... OH GOD PLEASE DON'T KILL ME PLEASE I'LL JUST DELETE IT JESUS CHRIST AAAAAH

I liked this picture, so I want other people to see it too.