Painful Quandary

• WWizards of the Coast2011-01-01
  Official Ruling
  Whenever an opponent casts a spell, Painful Quandary's ability triggers and goes on the stack on top of it. It will resolve before the spell does.
• WWizards of the Coast2022-10-14
  Official Ruling
  Whenever an opponent casts a spell, Painful Quandary's ability triggers and goes on the stack on top of it. It will resolve before the spell does.

Rulings via Scryfall