Rashi on Numbers 30:16/רש"י על במדבר ל׳:ט״ז

1אחרי שמעו [BUT IF HE SHALL AT ALL ANNUL THEM] AFTER HE HATH HEARD THEM i.e., after he has heard and confirmed them — that he had said, “I am content with it”, then if he turns and annuls it even on the same day (Sifrei Bamidbar 156:2).

2ונשא את עונה HE SHALL BEAR HER INIQUITY — He takes her place. We learn from here that he who makes another take a false step takes his place in respect to all punishments which he would incur (Sifrei Bamidbar 156:2).