Joining the Imam with the intention of offering the Sunnah Prayer since the time for Salah is not due yet

Q 2: If the Salah (Prayer) is offered before its due time, is it permissible to offer it with the Imam intending it as supererogatory prayer before the Fajr (Dawn) Prayer?

A: If you are sure that the Salah is performed before its due time, you have to draw your Imam's attention to that mistake and not intend it as a Sunnah prayer. You should indicate that matter to the Imam and if he admits his fault, praise be to Allah; otherwise, you have to tell his supervisor to save yourself from blame.Moreover, you should not offer Salah behind him as you know that he is offering Salah before its due time, because by that you agree with him in his mistake and this might tempt people to believe that he is doing the right thing.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.