Numbers 30:7

she must do everything that she vowed or promised unless her husband raises an objection when he hears about it.

Treasury of Scripture Knowledge

Summary

And her husband heard it, and held his peace at her in the day that he heard it: then her vows shall stand, and her bonds wherewith she bound her soul shall stand.

General references

Bible References

General references

Numbers 30:14
If he says nothing to her about it day after day, this means he decided that she must keep her vow or oath. She must keep it because he said nothing to her when he heard about it.