Iirc it was when Octavius first fought Rhino in Parkers body and he took Rhinos lower jaw off with one punch.I feel that's more about how jaw-droppingly powerful Peter Parker actually is, and that he's basically holding back all the time.
Part of the point of Spider-Man is he technically has the capacity to straight-up murder any of his usual opponents. He's way stronger than them, and way faster. His stories far more often revolve around him trying to save them from themselves; trying to stop whatever plot they're hatching because he's worried they'll go too far and will lose any chance for redemption. It's why so many of his villains have a direct personal connection; Doc Oc, the Lizard, the Goblins, etc.
I can't recall if that sequence is from the Superior Spider-Man series where Octavius inserts his own personality into Parker's head, taking control of him, but that's another series that really lays out exactly how self-limiting Peter Parker's always been, starting with Octavius realizing how many times Parker could have easily killed him and chose not to.