Assalaamu alaykom dear Shaykh. May Allaah preserve your health and your eemaan (faith). Occasionally, my family are a little late to pray the Maghrib, so when this happens, I pray the two rakʻahs (units of prayer) of the sunnah of the Maghrib before it because I do not want to miss out on the Sunnah. Is this permissible or am I making an innovation? May Allaah reward you.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

If you mean that you perform the regular Sunnah prayer that should be performed after the Maghrib before it, then this does not conform to the Sunnah. The scholars stated that it is invalid to perform the regular Sunnah prayer that should be performed after the obligatory prayer before it. Kashshaaf Al-Qinaaʻ reads:

"The time of the regular Sunnah prayer that should be performed before the obligatory prayer, such as the Sunnah of the Fajr and Thuhr prayers starts from the beginning of the time of the respective prayer until one performs the obligatory prayer. As for the regular Sunnah prayer that should be performed after the obligatory prayer such as those of the Maghrib and ʻIshaa', their time starts after the respective obligatory prayer is performed and lasts until the end of their times; they should not be performed before the obligatory prayers..."

The Shaafiʻi book Haashiyat Ar-Ramli ʻala Asna Al-Mataalib reads,"The regular Sunnah prayer that should be performed after the obligatory prayer should not be performed before it; its due time starts after performing the obligatory prayer..."

Hence, performing the regular Sunnah prayer that should be performed after the Maghrib before it is not adequate and does not conform to the Sunnah.

However, it is legislated to perform a two-rakʻah prayer before the Maghrib prayer aside from the reported regular Sunnah prayer that should be performed after it. This is not considered a bid'ah (religious innovation) because the Prophet said, "Perform (an optional) prayer before Maghrib prayer." He repeated it, and the third time he added, "for whoever wishes to do so," lest the people should take it as a Sunnah (regular tradition). [Al-Bukhari] It has been narrated that "the Prophet performed two rakʻahs before Maghrib." [Ibn Hibbaan]

Allaah knows best.