Dr. Ben Carson’s medical career has been well-documented over the years, including as the subject of a 2009 made-for-TV movie, “Gifted Hands,” which helped introduce the American public to the Johns Hopkins neurosurgeon.

One detail fewer people probably know about the famed pediatric neurosurgeon, according to The Daily Caller’s Matt Lewis, is that the first time that the 2016 Republican presidential candidate used a knife on someone was not in the operating room. Instead, according to Carson, it was in the middle of a heated conversation with a classmate when he was 14 years old, and it ended when he used a large campaign knife to stab him.

Carson told Lewis back in 2014:

“I had real anger issues. I would just fly off the handle and really become quite irrational and try to hurt people with baseball bats, hammers, whatever. In this particular case, I happened to have a large camping knife.

And, you know, one of my friends angered me. And I just lunged at his abdomen with the knife. Probably would have seriously injured or killed him, but he happened to have on a large metal belt buckle under his clothing, upon which the blade broke.”

Carson added:

“And, of course, he fled in terror. But I was more horrified than he was, because I realized that I was trying to kill somebody over nothing — and that I would never realize my dreams of becoming a physician.

And I would end up in jail, reform school, or the grave. And I just locked myself in the bathroom and started praying.”

Read More: Ben Carson’s Story About the First Time He Used a Knife on Someone Has an Important Life Lesson