This cap is from 4x22 "Lucifer Rising".
Click to see the full-sized cap.
Sam in that pivotal moment between killing Lilith and hearing Dean trying to stop him.
Ugh. I'm so tired. Sick of stressing out and tired of my neck hurting. :( At least I'm getting my VanCon photos posted. I'll try to get Day 2's set up today. *yawns* Have a good one, all. Wish I could say the same. *hugs*