Cutting Short the Sunnah before Zuhr

Q: Salaah-353: A person started performing the four Rakaahs Sunnah Salaah before the Fardh of Zuhr but then terminated the salaah by making Salaam after two Rakaahs because the Jamaa'ah had commenced. Can he suffice by performing two Rakaahs afterwards or does he need to complete four Rakaahs?

Answer: In the stated case, he will have to perform four Rakaahs salaah because these four Rakaahs are Sunnah with one Salaam. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2