question #3 Sahih Muslim 729, Book 6, Hadith 128 : What is the significance of performing Sunnah prayers in addition to the obligatory ones?

I prayed along with Allah’s Messenger (ﷺ) two rak’ahs before and two rak’ahs after the noon prayer, two rak’ahs after the sunset prayer and two rak’ahs after the ‘Isha’ prayer and two rak’ahs after the Friday prayer; and so far as the sunset, ‘Isha’ and Friday prayers are concerned, I observed (them) along with the Messenger of Allah (ﷺ) in his house.