"He shall not profane his word; he shall do according to all that issues from his mouth"—Numbers 30:3.
It is forbidden to violate one's verbal pledge, whether that pledge was worded as an oath or not.
Examples of such pledges:
- "If so-and-so occurs, or if I do this-and-this, all fruit – or fruit from this city – will become forbidden for me."
- "Wine/milk/fish are forbidden for me."
- The pleasure of my wife's [intimate company] is forbidden for me."
- Any pledge to bring a sacrifice or give an amount of money to charity or to a synagogue.