Eat your words

Eat your words: Aceitar publicamente que você estava errado sobre algo que você falou /confessar que estava errado a respeito de algo / admitir um erro

“You shouldn't say that to me. I'll make you eat your words.”

 “John was wrong about the election and had to eat his words.”

“I may eat my words, but I don't think Holly is going to be able to do this.” (www.thefreedictionary.com)