This is from Robin: Year One which is a miniseries about Dick Grayson's first year as Robin, and it's weird cause the first issue is pretty kid-friendly, and then this happens. It's a really good story, and I always recommend it if anyone asks to read Dick Grayson as Robin, but it's quite shocking, in the least. And directly after this Bruce fires Dick from being Robin for the first time. I'm not sure if this story is necessarily canon, but in my head it definitely is. I wish someone at DC would do another series similar to this.
From Robin: Year One issue 2