(Bamidbar 30:13) "Her husband has annulled them": If the husband annuls, they are annulled; if not, they are not annulled. If she said: "I know that any vow of mine that my husband would hear of he would annul," I might think that it is annulled. It is, therefore, written "Her husband has annulled them." If the husband annuls, they are annulled; if not, they are not annulled.
If he said to a caretaker: "Annul all the vows that my wife makes from now until I return from that place," and he did so, I might think that they would be annulled. It is, therefore, written "Her husband has annulled them." If the husband annuls, they are annulled; if not, they are not annulled. These are the words of R. Yoshiyah.
R. Yonathan says: We find in all places that a man's messenger is like the man himself. "and the L-rd will forgive her": If she vowed and he annulled it in his heart, and she went and broke (the vow wilfully), whence do we derive that she (still) requires forgiveness? From "and the L-rd will forgive her."