Similarly, if the sun begins to set before one finishes Asr, does that prayer become invalid? Thank you.
If the sun rises during the Fajr Salaat, then the Salaat will be
invalidated. However, if it sets during the Asr prayer, performance of
Salaat at this time will be Makrooh (detestable) but should be completed.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai