eat one’s words, to

To be forced to retract a statement, usually in a humiliating way. The term first appeared in a sixteenth-century tract by John Calvin on Psalm 62: “God eateth not his word when he hath once spoken.”
In 1618 Sir Walter Raleigh wrote in his memoirs, “Nay wee’le make you confesse . . . and eat your own words,” and in 1670 the expression appeared in John Ray’s collection of English proverbs.