Q: My in laws are having a surprise get-together one day before my mother-in-law's birthday. They said it's fine because there will be no cake and it's just a get-together. What should I do?
A. The underlying purpose of this get-together is her birthday which Muslims do not celebrate in any form; whether on the day, a day after or a day before. Gathering a day before does not now imply that it is correct. It will be best not to gather for this purpose, the time of gathering is irrelevant.
However if your non attendance will create animosity and discontent among yourselves, then just to keep the peace, attend the gathering but make an excuse to leave early, and make Istighfaar thereafter.
Allah Ta'aala knows best.
Mufti Siraj Desai