Answered by Shaykh Hamza Karamali, SunniPath Academy Teacher
What are the 6 rakats after maghrib mentioned by Imam Nawawi in the Maqasid (are they in addition to the two rakats sunnah)?
Q2. Are there any sunnah prayers to be performed before Isha?

In the Name of Allah, Most Merciful and Compassionate
A1. The 6 rakats mentioned in the Maqasid is probably salat al-awwaabeen (“the prayer of those who repeatedly turn to Allah”). This is a prayer that is different from the 2 rakah sunna mu’akkada prayer that is recommended after the maghrib prayer. It is also called salat al-ghafla (“the prayer of heedlessness”) because people normally neglect praying between maghrib and isha, being preoccupied instead with eating or sleep. It is optimally twenty rakas, and six rakas is considered a “middle amount”. It is based on a hadith related by Tirmidhi where the Prophet (Allah bless him and give him peace) is reported to have said, “Whoever prays six rakas between maghrib and isha will have twelve years of worship inscribed for him.” (Mughni al-Muhtaj, 1.343; Fath al-Allam)
A2. Imam Nawawi mentioned in his Majmu that it is sunna to pray two rakas before the isha prayer. This is based on a hadith related by Bukhari where the Prophet (Allah bless him and give him peace) said, “There is a prayer between every two adhans.” Al-Khatib al-Shirbini mentions that the “two adhans” are the iqama and the adhan. (Mughni al-Muhtaj, 1.335)
And Allah knows best.
Hamza.