Question 203) - What does a Munfarid do if he has prayed a Rak'ah or two of the Fard of Fajr or Maghrib and the Jama'ah commences?

A: If he has prayed a Rak'ah of Maghrib or Fajr he must break off his Salah whether he made Sajdah or not. He will also break off if he did not complete the Sajdah of the second Rak'ah. He will then join the Imam in these three scenarios. If he has made Salah of the second Rak'ah he will complete the Salah and not break it.

~ al-Quduri ~