Eat one's words

He didn't think I could do it, but I proved him wrong and made him eat his words.

This time, you have to eat your words, because, like it or not, you lost.

"Better retract that," she advised, "hadn't you?" "Why should I?" "Because if you're stupid enough to remain in Bombay, I'll make you eat your words one day."

However, in 1844, saner counsels prevailed, and Edgeley became the principal station—the directors eating their words once more by retaining the older station, which was renamed Heaton Norris.

Of course, if she [J. K. Rowling] has turned into a first-class writer with her forthcoming Potter book, I will happily, no, joyously, eat my words.