Cross (someone's) heart
Translation of "cross (someone's) heart" into Russian
cross (someone's) heart
дать честное слово
I cross my heart, I didn't take your book.
Я даю честное слово, я не брал твою книгу.
Definitions
To make a sincere promise or assurance, often used to emphasize that one is telling the truth or will keep a secret. The full phrase is often 'cross my heart (and hope to die)'.