cross my heart (and hope to die)
idiomPart ofcross
cross my heart (and hope to die) — idiom
1. Used to emphasize that you are telling the truth or will keep a promise.
1.idiom
Definition
Used to emphasize that you are telling the truth or will keep a promise.
Example
I didn't take your book, cross my heart.
Cross my heart, I will finish the project by Friday.