The Congregation Began While He Was Praying the Sunna

Question

If someone is praying a sunna or nafl in the front row and the congregation of the fard stands up [and begins], will the prayer of the one praying the sunna or nafl not be valid, as is commonly held?

Answer

The prayer does not become fasid (invalid). But he should complete his sunna or nafl in a lightened manner (takhfif) and join the congregation.

Source: Fatawa Mahmudiyya

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